Browsing by Author "Tanaka, H"

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    Magnetic structure of the S=1/2 quasi-two-dimensional square-lattice Heisenberg antiferromagnet Sr2CuTeO6
    (American Physical Society, 2016-02-26) Koga, T; Kurita, N; Avdeev, M; Danilkin, SA; Sato, TJ; Tanaka, H
    The magnetic structure of the double perovskite compound Sr2CuTeO6 was determined from neutron powder diffraction data. This material is magnetically described as an S=1/2 quasi-two-dimensional square-lattice Heisenberg model with antiferromagnetic nearest-neighbor and next-nearest-neighbor interactions. Sr2CuTeO6 undergoes a magnetic phase transition at TN≃29 K. The spin structure below TN is Néel antiferromagnetic on the square lattice, which means that the nearest-neighbor interaction (J1) is stronger than the next-nearest-neighbor interaction (J2), in contrast to other isostructural compounds such as Ba2CuWO6 and Sr2CuWO6, for which |J1|<|J2| is realized. ©2016 American Physical Society
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    Proceedings of the 10th International Particle Accelerator Conference
    (JACoW, 2019-05-19) Boland, MP; Tanaka, H; Button, D; Dowd, RT; Schaa, VRW; Tan, YRE
    The 10th International Particle Accelerator Conference (IPAC’19), will be held in Melbourne, Australia from May 19 -24, 2019. The venue will be the world-leading Melbourne Convention and Exhibition Centre (MCEC) located in the spectacular Southbank precinct and overlooking Melbourne city and Yarra River. IPAC is the main international event for the worldwide accelerator community and industry. Attendees will be presented with cutting-edge accelerator research and development results and gain the latest insights into accelerator facilities across the globe. With over 1000 delegates and 70 industry exhibits, this is a unique opportunity to network with, learn from and meet a wide range of decision makers, opinion leaders, buyers and new kids on the block. Melbourne has been ranked the Word’s Most Liveable City for seven years running and is also the gateway to some of Australia’s most scenic and beautiful regions including the Great Ocean Road, Yarra Valley, Mornington Peninsula, and Central Goldfields. Melbourne itself is home to world-class restaurants, galleries, shopping, and assorted cultural highlights. At IPAC’19, you will have the opportunity to meet and interact with accelerator scientists, engineers, students, and vendors while experiencing the world’s most liveable city.
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    Quantum magnetic properties of the spin-1/2 triangular-lattice antiferromagnet Ba2La2CoTe2O12
    (American Physical Society, 2018-11-05) Kojima, Y; Watanabe, M; Kurita, N; Tanaka, H; Matsuo, A; Kindo, K; Avdeev, M
    We report the crystal structure of Ba2La2CoTe2O12 determined by Rietveld analysis using x-ray powder-diffraction data. It was found from magnetic measurements that Ba2La2CoTe2O12 can be described as a spin-12 triangular-lattice antiferromagnet with easy-plane anisotropy at low temperatures. This compound undergoes a magnetic phase transition at TN=3.26K to an ordered state with the 120∘ structure. The magnetization curve exhibits the one-third plateau characteristic of triangular-lattice quantum antiferromagnets. The antiferromagnetic exchange interaction and the g factors parallel and perpendicular to the c axis were evaluated to be J/kB=22K,g∥=3.5, and g⊥=4.5, respectively. ©2018 American Physical Society
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    Successive phase transitions and magnetization plateau in the spin-1 triangular-lattice antiferromagnet Ba2La2NiTe2O12 with small easy-axis anisotropy
    (American Physical Society, 2019-08-22) Saito, M; Watanabe, M; Kurita, N; Matsuo, A; Kindo, K; Avdeev, M; Jeschke, HO; Tanaka, H
    The crystal structure and magnetic properties of the spin-1 triangular-lattice antiferromagnet Ba2La2NiTe2O12 are reported. Its crystal structure is trigonal R¯3, which is the same as that of Ba2La2NiW2O12 [Y. Doi et al., J. Phys.: Condens. Matter 29, 365802 (2017)]. However, the exchange interaction J/kB≃19 K is much greater than that observed in the tungsten system. At zero magnetic field, Ba2La2NiTe2O12 undergoes successive magnetic phase transitions at TN1=9.8 K and TN2=8.9 K. The ground state is accompanied by a weak ferromagnetic moment. These results indicate that the ground-state spin structure is a triangular structure in a plane perpendicular to the triangular lattice owing to the small easy-axis-type anisotropy. The magnetization curve exhibits the one-third plateau characteristic of a two-dimensional triangular-lattice Heisenberg-like antiferromagnet. Exchange constants are also evaluated using density functional theory (DFT). The DFT results demonstrate the large difference in the exchange constants between tellurium and tungsten systems and the good two-dimensionality of the tellurium system. ©2019 American Physical Society