44th Condensed Matter and Materials Meeting Holiday Inn, Rotorua, New Zealand 4-7 February 2020 Wagga 2020: 44th Condensed Matter and Materials Meeting Organizing Committee Dr Philip Brydon, University of Otago (chair) Prof. Tilo Söhnel, University of Auckland Dr Ben Mallett, University of Auckland 1 Wagga 2020: 44th Condensed Matter and Materials Meeting Contents Sponsors ................................................................................................................ 3 General Information .............................................................................................. 4 Program at a glance ............................................................................................... 5 Program ................................................................................................................. 6 Posters ................................................................................................................. 10 Memories of Wagga 2014 ................................................................................... 13 Talk Abstracts ..................................................................................................... 14 Poster Abstracts ................................................................................................... 55 Participant List .................................................................................................... 89 2 Wagga 2020: 44th Condensed Matter and Materials Meeting Sponsors We gratefully acknowledge the support of the following: 3 Wagga 2020: 44th Condensed Matter and Materials Meeting General Information Scientific program: The conference will take place at the Holiday Inn Rotorua. All lectures will be held in the Totara room. Session chairs and speakers are asked to adhere closely to the schedule for the oral program. A laptop, data projector, laser pointer and microphone will be available. Please check as early as possible the compatibility with the computer facilities provided. Posters should be mounted on Tuesday evening or Wednesday morning in the allocated space in the Kauri room (please refer to the number of your poster). Please remove all posters by Thursday night or Friday morning. Administration: Please wear your name tag at all times. Registration desk will be open from 3pm - 7pm on Tuesday for delegate registration and other matters regarding the conference. Questions or problems regarding the accommodation, please contact the hotel reception. Wireless internet access is available in the hotel. Please make sure to pay for any additional costs charged by you on your room number before your departure. Meals and refreshments: Lunch and dinner will be served in the Pohutu In room. Lunch will be served according to the program on Wednesday through Friday. Dinner will begin each night at 7:30pm. Morning and afternoon tea will be available in the conference room. Contact information: Holiday Inn Rotorua: 10 Tryon St, Whakarewarewa, Rotorua 3043 +64 7 348 1189 Organizing committee: Philip Brydon +64 21 088 73495 4 Wagga 2020: 44th Condensed Matter and Materials Meeting Program at a glance Tuesday Wednesday Thursday Friday 8:50 Opening 9:00 Grochala Schwerdtfeger Fehske Rachel Novelli O’Brien Menke Jayalatharachchi Bonca Jovic Goodacre Nawaz 10:30 Morning Tea Morning Tea Morning Tea 11:00 Karel Knibbe Granville Ulrich Tallon Maekawa Tretiakov Storey Kammermeier 12:00 Spasovski Chan Keser Prizes and closing Lunch Lunch Lunch 13:30 Ling Nielsen Narayanan Culcer Yick Lewis Prelovsek Park Photo 15:00 Afternoon Tea Afternoon Tea 15:30 Acharya Trodahl Henkel Holmes-Hewett Christopher Anton Jacobson Registration with 17:00 Tribute afternoon tea Posters Posters 19:30 Dinner Dinner Conference Dinner Quiz 5 Wagga 2020: 44th Condensed Matter and Materials Meeting Program Tuesday, 4th February 2020 15:00 – 19:00 Registration 19:00 Dinner Wednesday, 5th February 2020 08:50 – 09:00 Opening Philip Brydon, University of Otago, New Zealand Session chair: Chris Ling (University of Sydney) 09:00 – 09:30 Remarkable fluoroargentates(II) - the ultimate siblings of oxocuprate materials (invited) Wojciech Grochala, University of Warsaw, Poland 09:30 – 09:50 High-Temperature Majorana Fermions in Magnet-Superconductor Hybrid Systems Stephan Rachel, University of Melbourne, Australia 09:50 – 10:10 Stabilizing even-parity chiral superconductivity in Sr2RuO4 Henri Menke, University of Otago, New Zealand 10:10 – 10:30 Dirac nodal lines and flat-band surface state in the functional oxide RuO2 Vedran Jovic, GNS Science, New Zealand 10:30 – 11:00 Morning Tea Session Chair: Dimitrie Culcer (University of NSW) 11:00 – 11:30 The Anomalous Hall Effect of Antiferromagnetic Mn3Ge and Amorphous (invited) Ferromagnetic FexSi1-x and FeyCo1-ySi Julie Karel, Monash University, Australia 11:30 – 11:50 Increase of the stability range of the skyrmion phase in doped Cu2OSeO3 Clemens Ulrich, University of New South Wales, Australia 11:50 – 12:10 Tuning Skyrmion Hall effect via Engineering of Spin-orbit Interaction Oleg Tretiakov, University of New South Wales, Australia 12:10 – 12:30 Tuning Magnetic Frustration in Bixbyites Martin Spasovski, University of Auckland, New Zealand 12:30 – 13:30 Lunch Session Chair: Stephan Rachel (University of Melbourne) 13:30 – 14:00 FeMn3Ge2Sn7O16 : a Spin-liquid Candidate with a Perfectly Isotropic 2-D (invited) Kagome Lattice Chris Ling, University of Sydney, Australia 6 Wagga 2020: 44th Condensed Matter and Materials Meeting 14:00 – 14:20 Symmetry analysis of the ferroic transitions in the coupled honeycomb system (Fe, Co, Mn)4Ta2O9 Narendirakumar Narayanan, Australian National University, Australia 14:20 – 14:40 Neutron Study of Magnetic Phase Transition in SrCoO3 Thin Films Samuel Yick, University of New South Wales, Australia 14:40 – 15:10 Spin-liquid state in planar Heisenberg models (invited) Peter Prelovsek, Jozef Stefan Institute, Slovenia 15:10 – 15:40 Afternoon tea Session chair: Ben Mallett (University of Auckland) 15:40 – 16:00 Avalanches, Criticality and Correlations in Self-Organised Nanoscale Networks Susant Acharya, University of Canterbury, New Zealand 16:00 – 16:20 Investigation of lithium-vacancy diffusion in lithium titanate: A FPMD simulation study Pascal Henkel, Julius Liebig University Geissen, Germany 16:20 – 16:40 Exploring the novel garnet system of Li6.75-3xGaxLa3Zr1.75Ta0.25O12 Timothy Daniel Christopher, University of Auckland, New Zealand 16:40 – 17:00 Scanning Tunnelling Spectroscopy of the Indium Oxide (111) Surface Peter Jacobson, University of Queensland, Australia 17:00 – 19:00 Poster session 19:30 – 20:30 Dinner 20:30 Quiz Thursday, 6th February 2020 Session Chair: Holger Fehske (University of Greifswald) 09:00 – 09:30 From Sticky Hard Spheres to Lennard-Jones potentials and many-body (invited) expansions for rare gas solids Peter Schwerdtfeger, Massey University, New Zealand 09:30 – 09:50 Carbon molecules in space: a thermal Equation of State study of solid hexamethylenetetramine Giulia Novelli, Australian Nuclear Science and Technology Organization, Australia 09:50 – 10:10 Monodisperse Silver Clusters Stabilized by an Organic Network Vishakya Jayalatharachchi, Queensland University of Technology, Australia 10:10 – 10:30 X-ray photoelectron studies of vanadium oxide surfaces in the presence of water Dana Goodacre, University of Auckland, New Zealand 10:30 – 11:00 Morning Tea 7 Wagga 2020: 44th Condensed Matter and Materials Meeting Session Chair: Eva Anton (Victoria University of Wellington) 11:00 – 11:30 Electron Holography of high temperature superconductors (invited) Ruth Knibbe, University of Queensland, Australia 11:30 – 11:50 NMR and thermodynamic studies of cuprate high-Tc superconductors Jeff Tallon, Victoria University of Wellington, New Zealand 11:50 – 12:20 Towards a single-model description of cuprates in the pseudogap state (invited) James Storey, Victoria University of Wellington, New Zealand 12:20 – 12:40 Magnetic Ordering in Superconducting Sandwiches Andrew Chan, University of Auckland, New Zealand 12:40 – 13:40 Lunch Session Chair: Tilo Söhnel (University of Auckland) 13:40 – 14:00 Demonstrating the Hot Carrier Solar Cell Through Broadband Absorption and Resonant Carrier Extraction Michael Nielsen, University of New South Wales, Australia 14:00 – 14:20 Resonant Photovoltaic Effect in Doped Magnetic Topological Materials Dmitrie Culcer, University of New South Wales, Australia 14:20 – 14:40 Condensed Matter Terahertz Interactions Roger Lewis, University of Wollongong, Australia 14:40 – 15:00 Realization of an Acoustic Supercoupler using Density-Near-Zero Metamaterial Choon Mahn Park, Dong-A University, Korea 15:00 – 15:10 Photo 15:10 – 15:30 Afternoon tea Session Chair: Ruth Knibbe (University of Queensland) 15:30 – 16:00 Rare-earth nitrides: Mixed valence, strongly correlated heavy Fermions (invited) Joe Trodahl, Victoria University of Wellington, New Zealand 16:00 – 16:20 4f Conduction in Rare Earth Nitrides William Holmes-Hewett, Victoria University of Wellington, New Zealand 16:20 – 16:50 Superconducting computing memory using rare-earth nitrides (invited) Eva Anton, Victoria University of Wellington, New Zealand 16:50 – 17:00 Tribute: Ralph Severin (Sev) Crisp, Eric Raymond (Lou) Vance, and Geoff Wilson Trevor Finlayson, University of Melbourne, Australia Dan Gregg, Australian Nuclear Science and Technology Organization, Australia Glen Stewart, University of New South Wales, Canberra, Australia 17:10 – 19:00 Poster session 19:30 Conference dinner 8 Wagga 2020: 44th Condensed Matter and Materials Meeting Friday, 7th February 2020 Session Chair: Philip Brydon (University of Otago) 09:00 – 09:30 Exotic criticality and symmetry-protected topological states in dimerised fermion, (invited) boson and spin chain models Holger Fehske, University of Greifswald, Germany 09:30 – 9:50 Anomalous Spectral Broadening from an Infrared Catastrophe in 2D Quantum Antiferromagnets Matthew O’Brien, University of New South Wales, Australia 9:50 – 10:20 Spectral Function of the Holstein Polaron at Finite Temperature (invited) Janez Bonca, Jozef Stefan Institute, Slovenia 10:20 – 10:40 Ferromagnetic Ni1-xFex nanofibers produced by electrospinning Tehreema Nawaz, Victoria University of Wellington, New Zealand 10:40 – 11:00 Morning Tea Session Chair: Julie Karel (Monash University) 11:00 – 11:30 Topological electronic transport properties of magnetic Weyl semi-metal (invited) Co2MnGa Simon Granville, Victoria University of Wellington, New Zealand 11:30 – 11:50 Spin Mechatronics in Spintronics Sadamichi Maekawa, RIKEN, Japan 11:50 – 12:10 Inplane magnetoelectric response in bilayer graphene Michael Kammermeier, Victoria University of Wellington, New Zealand 12:10 – 12:30 Hydrodynamic electron flow in 2D semiconductor heterostructures Aydin Cem Keser, University of New South Wales, Australia 12:30 – 12:40 Presentations and closing Philip Brydon, University of Otago, New Zealand Ben Mallett, University of Auckland, New Zealand 12:40 – 13:40 Lunch 9 Wagga 2020: 44th Condensed Matter and Materials Meeting Posters All posters will be displayed in the Kauri room for the duration of the conference. 1. Topology from Interactions: Haldane-like Phase in the Extended Hubbard Model Roman Rausch, Kyoto University, Japan 2. New on the Physics Menu: Superconducting Sandwiches! Andrew Chan, University of Auckland, New Zealand 3. Control of the persistent spin helix lifetime by crystal orientation Daisuke Iizasa, Tohoku University, Japan 4. Magnetism in alloys of the rare-earth nitrides Jackson Miller, Victoria University of Wellington, New Zealand 5. High Magnetic Saturation Holmium-Terbium Thin-Films Alloys; Application in High- Tc machines Tane James Butler, Victoria University of Wellington, New Zealand 6. Topological superconductivity from the 2D Hubbard model Sebastian Wolf, University of Melbourne, Australia 7. Delocalisation of d-electrons within Transition Metal Doped Clusters: Pushing the Limits of the Superatom Model James Gilmour, Victoria University of Wellington, New Zealand 8. Development of a spin-injection field effect transistor utilizing Rare-earth Nitrides Kira Pitman, Victoria University of Wellington, New Zealand 9. Carbon-fibre incorporated CoSb3 based skutterudite facilitating colossal electrical conductivity fabricated by Field Assisted Sintering Method. Ridwone Hossain, University of Wollongong, Australia 10. Preparation and structural characterisation of pure and Te-doped Cu2OSeO3 Rosanna Rov, University of Auckland, New Zealand 11. Exploring the Pyrophosphate Series K2Cu1-xFexP2O7 Ryan Silk, University of Auckland, New Zealand 12. Development of whitlockite β-Ca3(PO4)2 phosphors Huihua Zhou, University of Auckland, New Zealand 10 Wagga 2020: 44th Condensed Matter and Materials Meeting 13. Crystal structure and thermoelectric properties of n-type Bi2-xCexO2Se ceramics Kyeongsoon Park, Sejong University, Korea 14. Exploring the Novel Pyrovanadate Series K2Mn1-xCoV2O7 Mark Smith, University of Auckland, New Zealand 15. Computational and Spectroscopic Studies on Magnetically Frustrated M’M’’3Si2Sn7O16 (M’ = Fe,Co; M’’=Fe,Mn) Structures Joseph Vella, University of Auckland, New Zealand 16. Magnonic Crystals: A Bottom-up Fabrication Approach Utilizing Polymer and Supramolecular Chemistry Daniel Clyde, University of Auckland, New Zealand 17. Temperature dependent terahertz spectra for glycine single crystal Jackson Allen, University of Wollongong, Australia 18. Temperature Dependence of Electron Delocalization in Mixed Valence Freudenbergite John Cashion, Monash University, Australia 19. Intrinsic Anomalous Hall Effect in Chiral D4h Superconductors Mathew Denys, University of Otago, New Zealand 20. A menagerie of strongly correlated phases on the decorated honeycomb lattice Henry Nourse, University of Queensland, Australia 21. Substitutional Doping of Trirutiline Phases, AB2O6 Sneh Patel, University of Auckland, New Zealand 22. Robustness of unconventional s-wave superconducting states against disorder David Cavanagh, University of Otago, New Zealand 23. Deformation Studies of Mg-PSZ under Compressive Loading Trevor Finlayson, University of Melbourne, Australia 24. Reinterpretation of physical property data for TmV2Al20 Wayne Hutchison, University of New South Wales, Canberra, Australia 25. Modelling 1D and 2D High-Temperature Superconducting Quantum Interference Filters Marc A. Gali Labarias, CSIRO Manufacturing, Australia 26. Bulk Currents in Artificial Graphene with a Magnetic Field Zeb Krix, University of New South Wales, Australia 11 Wagga 2020: 44th Condensed Matter and Materials Meeting 27. Characterising the local crystal field interaction for RFeO3 (R = Er, Ho) Glen Stewart, University of New South Wales, Canberra, Australia 28. Quantum size effects in topological-insulator nanostructures Ulrich Zuelicke, Victoria University of Wellington, New Zealand 29. Prediction of the spin triplet two-electron quantum dots in Si: towards controlled quantum simulations of magnetic systems Oleg Sushkov, University of New South Wales, Australia 30. Photoluminescence of Coscinodiscus sp. Diatoms Jiazun Wu, Victoria University of Wellington, New Zealand 31. Low-energy electron beam induced damage to organic molecules – limits to IPES application on organic molecules Gabriele Motta, Queensland University of Technology, Australia 32. Nonlinear optical response of the α-T3 model due to the nontrivial topology of the dispersion Jack Zuber, University of Wollongong, Australia 33. Magnonic Hydrogen Gas Sensing Mikhael Kostylev, University of Western Australia, Australia 34. Surveying the higher dimensions of the aperiodic composite nonadecane/urea Garry McIntyre, Australian Nuclear Science and Technology Organization, Australia 12 Wagga 2020: 44th Condensed Matter and Materials Meeting Memories of Wagga 2014 Waiheke Island, New Zealand, 4-7 February 2014 (thanks to Garry McIntyre) 13 Wagga 2020: 44th Condensed Matter and Materials Meeting Talk Abstracts 14 Wagga 2020: 44th Condensed Matter and Materials Meeting Avalanches, Criticality and Correlations in Self-Organised Nanoscale Networks Susant K. Acharya1, Joshua Brian Mallinson1, Shota Shirai1, Saurabh K. Bose1, Matthew D. Pike2, Edoardo Galli1, Matthew D. Arnold3, and Simon A. Brown1 1 MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury, 8140, Christchurch, New Zealand; 22Electrical and Electronics Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand; 3School of Mathematical and Physical Sciences, University of Technology Sydney, Australia Neuronal avalanches are one of the key characteristic features of signal propagation in the brain. [1] These avalanches originate from the complexity of the network of neurons and synapses, which are widely believed to form a self-organised critical system. Criticality is hypothesised to be intimately linked to the brain’s computational power [2] but efforts to achieve neuromorphic computation have so far focused on highly organised architectures, such as integrated circuits and regular arrays of memristor. To date, little attention has been given to developing complex network architectures that exhibit criticality and thereby maximize computational performance. We show here, using methods developed by the neuroscience community, that electrical signals from self-organised percolating networks of nanoparticles exhibit brain-like correlations and criticality. [3] Specifically, the sizes and durations of avalanches of switching events are power-law distributed, and the power-law exponents satisfy rigorous criteria for criticality. Additionally we show that both the networks and their dynamics are scale-free. These networks provide a low-cost platform for computational approaches that rely on spatiotemporal correlations, such as reservoir computing, and are a significant step towards creating neuromorphic device architectures. Fig. 1: The percolating network of nanoparticles in a simple two-terminal contact geometry. The different colours represent groups of particles that are in contact with one another. The zoomed region shows a schematic of the growth of an atomic filament within a tunnel gap (a switching event, that can be seen as synapse-like) when a voltage is applied. Bottom: The same network schematic presented so as to show the conducting pathways (black) which result from atomic filament formation within the gaps between groups. When the applied potential causes one tunnel gap between groups to be bridged by a conducting filament, the electric field across other tunnel gaps is intensified, leading to avalanches of switching events. References [1] Beggs, J. M. et al. ,J. Neurosci. 23, 11167 (2003). [2] Munoz, M. A. Rev. Mod. Phy. 90, 031001 (2018). [3] Mallinson, J. B. et al. Sci. Adv. 11, eaaw8438 (2019). 15 Wagga 2020: 44th Condensed Matter and Materials Meeting Superconducting computing memory using rare-earth nitrides E.-M. Anton, S. Devese, J. Miller, F. Ullstad, B. J. Ruck, H. J. Trodahl, F. Natali The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand Data centers are at the core of infrastructure providing internet, cloud computing and data storage. Their size and power consumption are growing rapidly to meet demand, and will become unsustainable within the next decade without breakthrough technologies or radical change in consumer behaviour. Data centers are predicted to use 5 -15 % of the global electricity and to exceed the carbon footprint of air travel as early as 2025, even when factoring in improvements in efficiency based on current semiconductor technology. Superconducting computing is a potential pathway to reduce energy consumption of data centers by a factor of 100, even taking into account the power needed for cryogenic cooling. On-going research efforts have made much progress in developing superconducting processors, but finding a compatible memory remains challenging. We are developing magnetic memory devices that are compatible with the cryogenic temperatures at which superconducting computers operate. The rare-earth nitrides are a promising group of materials for this task, as many are intrinsic ferromagnetic semiconductors with low Curie temperatures and they provide a range of different magnetic properties. Among them are hard and soft ferromagnets, a strong ferromagnet with near-zero magnetic moment and a superconductor itself, and they can be stacked easily in devices due to similar chemistry and lattice constants. This talk will present the current status of research on rare-earth nitrides for memory devices, and give an outlook to future applications. 16 Wagga 2020: 44th Condensed Matter and Materials Meeting Spectral Function of the Holstein Polaron at Finite Temperature J. Bonča,1,2 S. A. Trugman,3 M. Berçiu4 1 Faculty of Mathematics and Physics, University of Ljubljana, SI-1000 Ljubljana, Slovenia 2 J. Stefan Institute, SI-1000 Ljubljana, Slovenia 3 Los Alamos National Institute, 87544 Los Alanos, NM 4 Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada, V6T 1Z1 I will present the Holstein polaron spectral function on a one dimensional ring obtained using the finite–temperature (T) Lanczos method. After a brief introduction in to basic properties of the model I will present most important features of the electron spectral function. With increasing T additional features in the spectral function emerge even at temperatures below the phonon frequency. We observe a substantial spread of the spectral weight towards lower frequencies and the broadening of the quasiparticle (QP) peak. In the weak coupling regime the QP peak merges with the continuum in the high-T limit. In the strong coupling regime the main features of the low–T spectral function remain detectable up to the highest T used in our calculations. The effective polaron mass shows a non–monotonic behavior as a function of T at small phonon frequency but increases with T at larger frequencies. The self energy remains k−independent even at elevated T in the frequency range corresponding to the polaron band while at higher frequencies it develops a distinguishable k−dependence. Analytical expressions for the first few frequency moments are derived and they agree well with those extracted from numerical calculations in a wide-T regime. Finally, I will also discuss some relaxation properties of the electron coupled to various bosonic excitations [2]. References [1] J. Bonča, S. A. Trugman, and M. Berçiu, Phys. Rev. B 100, 094307 (2019). [2] J. Kogoj, M. Mierzejewski and J. Bonča, Phys. Rev. Lett., 117, 227002 (2016). 17 Wagga 2020: 44th Condensed Matter and Materials Meeting Magnetic Ordering in Superconducting Sandwiches A. Chan1,2,4,5, N.J. van der Heijden2,4, T. Söhnel2,4, M.C. Simpson1,2,3,4,5, K.C. Rule6, G.L. Causer6, W.-T. Lee6, C. Bernhard7, B.P.P. Mallett1,2,4,5 1The Photon Factory, The University of Auckland, New Zealand 2School of Chemical Sciences, The University of Auckland, New Zealand 3Department of Physics, The University of Auckland, New Zealand 4The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand 5The Dodd-Walls Centre for Photonic and Quantum Technologies, New Zealand 6Australian Nuclear Science and Technology Organization, Lucas Heights, Sydney, Australia 7Department of Physics, University of Fribourg, Switzerland Our cuprate-manganite ‘superconducting sandwich’ multilayers exhibit a highly unusual magnetic-field induced insulating-to-superconducting transition, contrary to the commonly held understanding that magnetic fields are detrimental to superconductivity [1, 2]. This new behaviour is a result of the specific magnetic and electronic properties of the manganite coupling with the cuprate (YBa2Cu3O7-δ, YBCO). Due to the specific manganite composition, Nd0.65(Ca0.7Sr0.3)0.35MnO3 (NCSMO), we hypothesize the behaviour to originate from CE-type antiferromagnetic ordering as well as charge and orbital ordering [3]. Zero-field cooled polarized neutron reflectometry (PNR) data in Fig 1(A) shows a sizable spin-flip (R+-) signal which may result from disordered ferromagnetic domains which sum to give a vanishing macroscopic magnetization. Initial elastic neutron scattering measurements performed on 100 nm thin film NCSMO display signatures of magnetic ordering (Fig 1(B)). Future neutron scattering measurements will look at the modification of magnetic order in a superlattice to better understand the relationship between NCSMO magnetization and our newly discovered insulating-to-superconducting transition. Fig. 1: (A) PNR profiles for a NCSMO20nm-YBCO7nm/NCSMO20nm trilayer after zero-field cooling to 7 K. Inset show corresponding nuclear and magnetic scattering length densities (SLDs) obtained from best fits to the data in (A). Plot (B) show zero-field cooled elastic neutron scattering data along the [h02] direction for a 100 nm thin film NCSMO. Black arrows indicate incommensurate satellite peaks. References [1] B. Mallett et al. Phys. Rev. B. 94, 180503(R) (2016) [2] E. Perret et al. Comms. Phys. 45, 1-10 (2018) [3] Y. Tokura. Rep. Prog. Phys. 69, 797-851 (2006). 18 Wagga 2020: 44th Condensed Matter and Materials Meeting Exploring the novel garnet system of Li6.75-3xGaxLa3Zr1.75Ta0.25O12 Timothy Christopher 1,2, Saifang Huang 3, Peng Cao3, Tilo Söhnel 1,2 1 School of Chemical Sciences & Centre of Green Chemical Science, University of Auckland, Auckland, New Zealand 2 MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, New Zealand 3 Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand Lithium garnet oxides have been put forward as a solid-state alternative for Li-ion electrolytes since the Li+ conducting abilities of Li7La3M2O12 (M = Ta, Nb) was discovered in 2003. [1] These solid-state materials exhibit physical and chemical properties desired for more efficient and safer Li-ion battery electrolytes. [2] Lithium garnet oxides can exist in tetragonal and cubic phase isomorphs with the latter exhibiting higher conductivities. Li7La3Zr2O12 undergoes a phase transition from cubic to tetragonal due to the thermodynamic unstable nature of the cubic arrangement. [3] Ionic conductivities of up to 1x10- 3 S cm-1 have been reported for cubic phase garnet materials of Li6.4La3Zr1.4Ta0.6O12. [4] Here we present a dual doped garnet series of Li6.75-3xGaxLa3Zr1.75Ta0.25O12 and attempt to mimic the high conductivities seen in that Li6.4La3Zr1.4Ta0.6O12. Successful synthesis of the proposed series was achieved via standard solid-state sintering from gallium doping up to x = 0.5. The garnet structure of x = 0.1 is shown in Figure 1. X-ray and neutron source diffraction characterisation revealed Ga has a preference to occupy the Li tetrahedral (Li24d) site over the octahedral (Li96h) site. High-temperature neutron diffraction studies show the relationship between temperature, Ga content and Li displacement between the Li24d and Li96h sites. With increasing temperature and increasing Ga content, the Li96h site occupancy increased with Li24d site decreasing. Ionic conductivity is shown to be dependent on the Ga/Li content within the garnet. Fig. 1: Proposed crystal structure of cubic phase Li6.45Ga0.1La3Zr1.75Ta0.25O12 refined from neutron powder diffraction data. Li - orange, Ga - purple, La - blue, Zr - grey, Ta - cyan, O– red. References [1]. V. Thangadurai, et al., Journal of the American Ceramic Society, 2003, 86, 437-440. [2]. V. Thangadurai, et al., Chemical Society Reviews, 2014, 43, 4714-4727. [3]. G. Larraz, et al., Journal of Materials Chemistry A, 2013, 1, 11419-11428. 19 Wagga 2020: 44th Condensed Matter and Materials Meeting Resonant photovoltaic effect in doped magnetic topological materials Pankaj Bhalla1,2, Allan H. MacDonald3, Dimitrie Culcer2,4 1Beijing Computational Science Research Center, Beijing 100193, China 2ARC Centre of Excellence for Future Low-Energy Electronics Technologies, UNSW Node, Sydney 2052, Australia 3Department of Physics, The University of Texas at Austin, Austin TX78712, USA 4School of Physics, The University of New South Wales, Sydney 2052, Australia The non-linear optical response of clean undoped semiconductors contains a static intrinsic term - the shift current. We have recently shown that when Kramers degeneracy is lifted, the second order dc response of doped topological materials and semimetals to an ac electric field becomes large at the interband absorption threshold in clean nearly isotropic materials. We refer to this effect, which results from an interesting interplay between inter-band coherence and intra-band occupation number response, as the resonant photovoltaic effect (RPE). We evaluate the RPE for a model of the surface states of Bi2Te3 coupled to in-plane magnetic order due to either bulk doping or proximity coupling [1]. Fig. 1: RPE due to magnetized TI surface states with different values of the warping coefficient . Blue curve: experimental value of  for Bi2Te3. References [1] P. Bhalla, A. H. MacDonald, and D. Culcer, arXiv:1910:06570. 20 Wagga 2020: 44th Condensed Matter and Materials Meeting Exotic criticality and symmetry-protected topological states in dimerised fermion, boson and spin chain models 
 S. Ejima1, F. Essler2, F. Lange1, Y. Ohta3, K. Sugimoto3, T. Yamaguchi3, H. Fehske1 1Institute of Physics, University Greifswald, 17489 Greifswald, German 2Rudolf Peierls Centre for Theoretical Physics, Oxford University, Oxford OX1 3NP, 3Center for Frontier Science, Chiba University, Chiba 263-8522, Japan Combining numerical density-matrix renormalisation group techniques and field theory we analyse the ground-state properties of several paradigmatic dimerised quantum lattice models in one dimension. First, we explore the quantum phase transition (QPT) between Peierls and density-wave (DW) states in the half-filled, extended Hubbard model with explicit bond dimerisation. We show that the critical line of the continuous Ising transition terminates at a tricritical point, belonging to the universality class of the tricritical Ising model with central charge c=7/10. Above this point, the QPT becomes first order. The entanglement spectrum shows that dimerised Peierls insulator is a symmetry-protected topological (SPT) state. By menas of bosonisation we describe the transition region in terms of a triple sine-Gordon model. The field theory predictions for the power-law (exponential) decay of the density-density (spin- spin) and bond-order-wave correlation functions are in excellent agreem ent with our numerical data. Secondly, we consider the dimerised extended Bose-Hubbard model and show that an SPT Haldane insulator appears between dimerised Mott and DW insulating phases, at weak Coulomb interactions, for filling factor one. Analysing the critical behaviour of the model, we prove that the phase boundaries of the Haldane phase to Mott insulator and DW states belong to the Gaussian and Ising universality classes with c=1 and c=1/2, respectively, and merge in a tricritical point. Furthermore, we demonstrate a direct Ising QPT between the dimerised Mott and DW phases above the tricritical point. Thirdly, we demonstrate that a nontrivial SPT Haldane phase also exists in dimerised spin-1 XXZ chain with single- ion anisotropy D, up to a critical dimerisation above which the Haldane phase disappears. In addition, the ground-state phase diagram exhibits large-D and antiferromagnetically ordered phases. Again, for weak dimerisation, the phases are separated by Gaussian and Ising QPTs. One of the Ising transitions terminates in a critical point in the universality class of the dilute Ising model. We comment on the relevance of our results to experiments on quasi-one-dimensional anisotropic spin-1 quantum magnets. References [1] S. Ejima, F. H. L. Essler, F. Lange, and H. Fehske, Phys. Rev. B 93, 235118 (2016). [2] S. Ejima, T. Yamaguchi, F. H. L. Essler, F. Lange, Y. Ohta, and H. Fehske, SciPost Phys. 5, 059 (2018). [3] K. Sugimoto, S. Ejima, F. Lange, and Fehske, Physical Review A 99, 012122 (2019). 21 Wagga 2020: 44th Condensed Matter and Materials Meeting X-ray photoelectron studies of vanadium oxide surfaces in the presence of water Dana Goodacre1,2, Hendrik Bluhm3, Monika Blum3, Tilo Söhnel1,2, Kevin Smith4 1 School of Chemical Sciences, The University of Auckland, Auckland 1010, New Zealand. 2 The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand. 3 Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. 4 Department of Physics, Boston University, Boston, Massachusetts 02215, USA. Surface science experiments where chemical species are quantified typically rely on ultra-high vacuum conditions, which do not closely mimic the conditions present in catalytic or environmental processes. Ambient pressure X-ray photoelectron spectroscopy (AP-XPS) is a technique that has allowed researchers to bridge this pressure gap and investigate what happens when the first few monolayers of water adsorb on various metal oxide materials.1 Here, it is applied to vanadium oxides, which are extensively used as industrial catalysts. The wide variety of oxidation states available in vanadium oxides makes them valuable for oxygen transfer reactions, where water may be present as an intermediate and in the atmosphere as the reaction is carried out.2 Using the beamline 11.0.2. AP-XPS system at the Advanced Light Source in Berkeley California, several oriented VO2 films with various substrates and surface compositions have been investigated, at catalytically relevant temperatures up to 400 °C and water vapour pressures up to 2 Torr. The AP-XPS spectra have been fit with peaks corresponding to adsorbed hydroxide and molecular water (Fig. 1), and the coverage as a function of relative humidity has been determined. The trends observed give further insights into the fundamental behaviour of oxides in the presence of water. Fig. 1: Representative fit of O 1s and V 2p region (left) and graphical representation (right) of a vanadium oxide surface in the presence of water. References (1) Starr, D. E.; Liu, Z.; Havecker, M.; Knop-Gericke, A.; Bluhm, H. Investigation of Solid/Vapor Interfaces Using Ambient Pressure X-Ray Photoelectron Spectroscopy. Chem. Soc. Rev. 2013, 42 (13), 5833–5857. https://doi.org/10.1039/C3CS60057B. (2) Surnev, S.; Ramsey, M. G.; Netzer, F. P. Vanadium Oxide Surface Studies. Prog. Surf. Sci. 2003, 73 (4), 117–165. https://doi.org/https://doi.org/10.1016/j.progsurf.2003.09.001. 22 Wagga 2020: 44th Condensed Matter and Materials Meeting Topological electronic transport properties of magnetic Weyl semi-metal Co2MnGa S. Granville1,2, Y. Zhang1,2, T. Butler1, G. Dubuis1,2 1Robinson Research Institute, Victoria University of Wellington, Wellington, New Zealand 2MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand Topologically interesting materials that are also magnetic are expected to be particularly important for the study of novel topological phases in condensed matter. The coupling of magnetic and transport properties in such materials could allow for spin topotronic devices, that take advantage simultaneously of the magnetic and topological physics. For instance, there are claims that ferromagnetic topological materials may allow the quantum anomalous Hall effect state, normally only seen below 10 K, to persist to room temperature. Excitingly, very recent results indicate that Heusler alloy Co2MnGa could be a room-temperature ferromagnetic Weyl semi-metal, a material with protected electronic states due to a topological band structure [1-3]. In this presentation I will show the signatures of these topological states are visible in magnetoelectric and magneto-thermoelectric measurements in thin films of Co2MnGa. Thin films of Co2MnGa set new room temperature records of the anomalous Hall and anomalous Nernst effects. For thinner films, the anomalous Hall effect weakens, and we discuss the implications of this for exploiting the Weyl-like characteristics of Co2MnGa in thin film devices. Fig. 1: Anomalous Hall angle vs anomalous Hall conductivity of magnetic materials, highlighting Weyl semi-metals, including Co2MnGa. Adapted from Nat. Phys. 14, 1125 (2018). References [1] A. Sakai et al., Nature Physics 14,1119–1124 (2018) [2] K. Manna et al., Phys. Rev. X 8, 041045 (2018) [3] I. Belopolski et al., Science 365, 1278-1281 (2019) [4] J. Kübler et al., Europhys. Lett. 114, 47005 (2016) [5] G. Chang et al., Phys. Rev. Lett. 119, 156401 (2017) 23 Wagga 2020: 44th Condensed Matter and Materials Meeting Remarkable fluoroargentates(II) - the ultimate siblings of oxocuprate materials W. Grochala1 1 University of Warsaw, CeNT, Zwirki i Wigury 93, 02089 Warsaw Poland Coinage group metals differ considerably from each other in terms of chemistry and physics. One particularly interesting manifestation of differences is offered by divalent state, which is enormously common and well-studied for copper, much less so for silver, while it is represented by only a handful of stoichiometries for gold. Here I will focus on compounds of divalent silver, notably fluorides. There are over a hundred of distinct stoichiometries known, most of them featuring magnetically isolated Ag(II) centers. However, some are known bearing direct Ag-F-Ag linkers (mostly in one dimension, seldom in two), which favour transmission of strong superexchange interactions. Here, I will discuss uniqueness of the crystal, electronic and magnetic structures as well as high pressure behavior of these compounds. Ultimately I will show what similarities and differences exist between them and undoped copper(II) oxides – precursors of the family of high-TC superconductors [1-9]. The prospect for achieving extremely strong antiferromagnetic superexchange in 2D [10] and 1D materials [7], as exemplified by AgF2 and AgFBF4, respectively, will be discussed. The former compound shows profound similarities to La2CuO4, with magnetic superexchange constant reaching 70 meV (2/3 of that for the copper compound). On the other hand, AgFBF4 features straight 1D [AgF+] chains with magnetic superexchange constant exceeding 300 meV. This value is second to none amongst all chemical systems explored so far, and it is followed by 241 meV observed previously for Sr2CuO3 cuprate. Simultaneously, AgFBF4 exhibits magnetic anisotropy which is 2 orders of magnitude higher than that for its oxocuprate rival, rendering the former the reference 1D antiferromagnet. References [1] ANGEW CHEM INT ED ENGL 40(15): 2742-2781 2001 [2] CHEMPHYSCHEM 4(9): 997-1001 2003 [3] NATURE MATER 5(7): 513-514 2006 [4] PHYS STAT SOL RRL 2(2): 71-73 2008 [5] ANGEW CHEM INT ED ENGL 49(9): 1683-1686 2010 [6] CHEM COMMUN 49(56): 6262-6264 2013 [7] ANGEW CHEM INT ED ENGL 56(34): 10114–10117 2017 [8] PHYS REV B 96(15): 155140 2017 [9] INORG CHEM 56(23): 14651–14661 2017 [10] PNAS 116(5): 1495–1500 2019 24 Wagga 2020: 44th Condensed Matter and Materials Meeting Investigation of lithium-vacancy diffusion in lithium titanate: A FPMD simulation study P. Henkel1,2, D. Mollenhauer1,2 1Institute of Physical Chemistry, Justus Liebig University Giessen, Giessen, Germany 2Center of Materials Research (LaMa), Justus Liebig University Giessen, Giessen, Germany The requirements to mobile devices are constantly increasing. A limiting factor is the energy supply. Over the last decades, lithium-ion batteries (LIBs) have emerged as a promising key technology for these. The ion transport through cathode, electrolyte and anode is an essential factor for the performance of an LIB. Therefore lithium titanate (LTO) is an auspicious anode material [1]. Essential properties of LTO are its chemical stability against metallic Li and its small volume-change during the Li-uptake, for which a phase transformation takes place from the Li-poor (Li4Ti5O12) to the Li-rich (Li7Ti5O12) phase [2]. The Li-ions occupy in the lithium-poor phase all 8a- and 5/6 of the 16d-Wyckoff positions. For a more precise understanding of lithium vacancy transport in LTO, we considered in our calculations a vacancy defect concentration of about 10% in the lithium-poor phase and investigated the Li-ion transport in the temperature range of 800K - 1000K using first principles molecular dynamic simulations (FPMD). Our simulations indicate that the lithium vacancy diffusion can take place via two diffusion paths: I) from an 8a- to an 8a-position – which is more efficient from an energetic point of view [4] – and II) from an 8a- to a 16d-position (see Fig 1). Fig. 1: Lithium-vacancy diffusion paths I) 8a ⇌ 8a and II) 8a ⇌ 16d within the Li-poor LTO structure. The aim of our FPMD simulation is to characterize the lithium vacancy diffusion paths more precisely by considering several vacancies and their interaction. Firstly, the simulations give evidence that the ion transport mainly takes place via the 8a ⇌ 8a path. Secondly, after a short simulation time, two out of three lithium vacancies are trapped in a 16d-position. Therefore, the vacancy interaction and their orientation to each other is essential. Also, a back diffusion of path I) is determined, which occurs by a factor of 1:2 to path I) and does not contribute to the Li-ion transport [4]. References [1]. M. Gockeln et al., Nano Energy 49, 464-573 (2018). [2]. T. Ohzuku, A. Ueda, and N. Yamamoto,J. Electrochem. Soc.142, 1431 (1995). [3]. M. Wagemaker et al., J. Phys. Chem. B 113, 224-230 (2009). [4]. P. Henkel, J. Janek, D. Mollenhauer, Manuscript to be submitted. 25 Wagga 2020: 44th Condensed Matter and Materials Meeting 4f Conduction in Rare Earth Nitrides W. F. Holmes-Hewett1, R. G. Buckley2, B. J. Ruck1, F. Natali1 and H. J. Trodahl1 1The MacDiarmid Institute for Advanced Materials and Nanotechnology and The School of Chemical and Physical Sciences, Victoria University of Wellington 2The MacDiarmid Institute for Advanced Materials and Nanotechnology and Robinson Research Institute, Victoria University of Wellington The influence of the 4f band on electrical transport in SmN and NdN promises a new class of simply structured NaCl materials, the rare earth nitrides, in which to investigate heavy Fermion systems. The 4f levels of the semiconducting rare earth nitrides span the conduction band and along with the control of carrier concentration, via doping with nitrogen vacancies, gives the potential for the Fermi energy to be tuned into the 4f band. SmN and NdN stand out with 4f bands predicted to meet the 5d, near the conduction band minimum [1]. Measurements of an enhanced anomalous Hall effect in each material give clear evidence for mobile electrons in the 4f band [2,3]. Optical measurements have now located the 4f bands as forming the conduction band minimum in both SmN and NdN, in close proximity to the 5d band [3,4]. Transport measurements will be presented of an enhanced anomalous Hall effect showing evidence of conduction in the 4f band (Figure 1) and optical spectroscopy that places the 4f band at the conduction band minimum in SmN and NdN. The role played by the 4f band on conduction in SmN and NdN indicates the rare earth nitrides present a series of simply structured materials ideally suited for the study of heavy Fermion systems. Fig. 1: Measurements of the Hall resistivity in SmN (blue), NdN (red), and GdN (orange). References [1] P. Larson, Walter R. L. Lambrecht, Athanasios Chantis, and Mark van Schilfgaarde, Phys. Rev. B 75, 045114 (2007). [2] W. F. Holmes-Hewett, F. H. Ullstad, B. J. Ruck, F. Natali and H. J. Trodahl, Phys. Rev. B 98, 235201 (2018). [3] W. F. Holmes-Hewett, R. G. Buckley, B. J. Ruck, F. Natali and H. J. Trodahl, Phys. Rev. B, 100, 195119 (2019). [4] W. F. Holmes-Hewett, R. G. Buckley, B. J. Ruck, F. Natali and H. J. Trodahl, Phys. Rev. B, 99, 205131 (2019). 26 Wagga 2020: 44th Condensed Matter and Materials Meeting Scanning Tunnelling Spectroscopy of the Indium Oxide (111) Surface Peter Jacobson1, Margareta Wagner2, Martin Setvin2, Michael Schmid2, Ulrike Diebold2 1School of Mathematics and Physics, The University of Queensland, QLD 4072, Brisbane, Australia 2Institute of Applied Physics, TU Wien, 1040 Vienna, Austria Indium oxide (In2O3) is a ubiquitous material in consumer electronic displays and photovoltaics due to an ideally matched optical transmission window and, unusual for a wide bandgap semiconductor, metallic conduction at room temperature. The exceptional functionality of many In2O3 devices stems from the presence of a near surface electron accumulation layer and the formation of a two-dimensional electron gas (2DEG) decoupled from the bulk electronic states. When In2O3 is paired with organic materials, a near universal fabrication step is the introduction of a thin organic buffer layer to improve the charge injection efficiency from the 2DEG to the organic active layer. Using a combination of atomic force microscopy and scanning tunnelling spectroscopy, we probe the structure and density of states (DOS) at the prototypical copper phthalocyanine (CuPc) - In2O3 interface. Differential conductance (dI/dV) measurements show that, in some instances, narrow gaps form at the Fermi level. This talk will discuss the possible origin of these gaps and the relevance to devices. 27 Wagga 2020: 44th Condensed Matter and Materials Meeting Monodisperse Silver Clusters Stabilized by an Organic Network V. Jayalatharachchi1, J. MacLeod1, J. Lipton-Duffin1,2 1 School of Chemistry Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, 4001-Australia 2 Institute for Future Environments, Queensland University of Technology, Brisbane, 4001 QLD, Australia In this study, we investigate 7-atom metal clusters coordinated by deprotonated carboxylic acid molecules on Ag(111) [1, 2]. The chemical and spatial precision of these types of monodisperse clusters of atoms have important implications for catalysis and energy production [3]. Deprotonation was examined by X-ray photoemission spectroscopy (XPS) and scanning tunnelling microscopy (STM), Fig.1 (a), while changes in the valence band region were interrogated by ultraviolet photoelectron spectroscopy (UPS). We used near edge X-ray absorption fine structure spectroscopy (NEXAFS), Fig.1 (b) in these experiments to confirm that the molecular core remains planar after deprotonation of the carboxylic/carboxylate groups via C-K edge/ O-K edge measurements. Careful study of the chemical and electronic structure of these clusters will allow us to better understand how to use organic molecules to engineer arrays of single-atom catalysts on surfaces, with the goal of tailoring these 2D materials systems for reactivity and selectivity in targeted catalysed reaction. a) b) Fig. 1: a) STM image of periodic metal-coordinated structure b) C K-edge NEXAFS data of fully deprotonated surface References [1]. Svane, K.L., et al., The Journal of Chemical Physics, (2018). [2]. Lipton-Duffin, J., M. Abyazisani, and J., MacLeod, et al., Chemical Communications, (2018). [3]. Svane, K. L., Baviloliaei, M. S., Hammer, B., & Diekhöner, L., et al., The Journal of Chemical Physics, (2018). 28 Wagga 2020: 44th Condensed Matter and Materials Meeting Dirac nodal lines and flat-band surface state in the functional oxide RuO2 Vedran Jovic,1,2 Roland J. Koch,1 Swarup K. Panda,3 Helmuth Berger,4 Philippe Bugnon,4 Arnaud Magrez,4 Kevin E. Smith,2,5 Silke Biermann,3,6 Chris Jozwiak,1 Aaron Bostwick,1 Eli Rotenberg,1 and Simon Moser1,7,* 1Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 2School of Chemical Sciences and Centre for Green Chemical Sciences, University of Auckland, Auckland 1142, New Zealand 3Centre de Physique Théorique, Ecole Polytechnique, CNRS-UMR7644, Université Paris-Saclay, 91128 Palaiseau, France 4Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland 5Department of Physics, Boston University, Boston, Massachusetts 02215, USA 6Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France 7Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany The efficiency and stability of RuO2 in various applications has made this material a subject of intense fundamental and industrial interest. The surface functionality is rooted in its electronic and magnetic properties, determined by a complex interplay of lattice-, spin-rotational, and time-reversal symmetries, as well as the competition between Coulomb and kinetic energies. This interplay was predicted to produce a network of Dirac nodal lines (DNLs), where the valence and conduction bands touch along continuous lines in momentum space. Here we uncover direct evidence for three DNLs in RuO2 by angle-resolved photoemission spectroscopy. These DNLs give rise to a flat-band surface state that is readily tuned by the electrostatic environment, and that presents an intriguing platform for exotic correlation phenomena. Our findings support high spin-Hall conductivities and bulk magnetism in RuO2 and are likely related to its functional properties. 29 Wagga 2020: 44th Condensed Matter and Materials Meeting Inplane magnetoelectric response in bilayer graphene M. Kammermeier1, P. Wenk2, U. Zuelicke1 1School of Chemical and Physical Sciences an MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington,, New Zealand 2Department of Theoretical Physics, University of Regensburg, Germany A graphene bilayer shows an unusual magnetoelectric response whose magnitude is controlled by the valley-isospin density, making it possible to link magnetoelectric behaviour to valleytronics. Complementary to previous studies, we consider the effect of static homogeneous electric and magnetic fields that are oriented parallel to the bilayer's plane. Starting from a tight-binding description and using quasidegenerate perturbation theory, the low-energy Hamiltonian is derived, including all relevant magnetoelectric terms whose prefactors are expressed in terms of tight-binding parameters. We confirm the existence of an expected axion-type pseudoscalar term, which turns out to have the same sign and about twice the magnitude of the previously obtained out-of-plane counterpart. Additionally, small anisotropic corrections to the magnetoelectric tensor are found that are fundamentally related to the skew interlayer hopping parameter γ4. We discuss possible ways to identify magnetoelectric effects by distinctive features in the optical conductivity. References [1]. M. Kammermeier, Phys. Rev. B. 100, 075421 (2019). 30 Wagga 2020: 44th Condensed Matter and Materials Meeting The Anomalous Hall Effect of Antiferromagnetic Mn3Ge and Amorphous Ferromagnetic FexSi1-x and FeyCo1-ySi J. Karel1,2 1 Department of Materials Science and Engineering, Monash University, Melbourne, Australia 2 ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Melbourne, Australia Magnetoresistive random access memory (MRAM) utilizing spin orbit torque (SOT) based switching has emerged as a promising non-volatile memory candidate, and amorphous materials offer a unique prospect with respect to this technology. They lack long range order, and theory has predicted that disorder may lead to an enhancement in spin orbit torques.1,2 Moreover, amorphous materials are extremely tolerant to defects, meaning less stringent manufacturing requirements and thus lower costs. The mechanisms used to describe the spin Hall effect (SHE) borrow directly from the physics of the AHE; therefore, a large AHE may point to a large SHE and a potential application in SOT-MRAM. The first part of this talk will present a study of the anomalous Hall effect (AHE) in a series of amorphous FexSi1-x and Fe1-yCoySi (0