Browsing by Author "Fujioka, F"

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    Comparison of the magnetic and crystal field excitations in orthorhombically distorted vanadates and multiferroic manganites
    (Australian Institute of Nuclear Science and Engineering, 2012-11-15) Reynolds, N; Rovillain, P; Narayanan, N; Fujioka, F; Tokura, Y; Danilkin, SA; Mulders, AM; McIntyre, GJ; Ulrich, C
    Magnetism and ferroelectricity are both exciting physical properties and are used in everyday life in sensors and data storage. In multiferroic materials both properties coexist. They offer a great potential for future technological applications like the increase of data storage capacity or in novel senor applications. We have performed a comparative inelastic neutron scattering (INS) investigation on a series of vanadates, in particularly TbV0{sub 3} DyV0{sub 3}, PrV0{sub 3}, and CeV0{sub 3}, with their multiferroic Mn-counterparts. The Vanadates are isostructural to the multiferroic materials TbMnO{sub 3} and DyMn0{sub 3}, but posses a collinear antiferromagnetic spin arrangement below TN ≈110 K instead of a cycloidal spin structure below TFE 28 ≈K. By using inelastic neutron scattering we have obtained the spin wave dispersion relation and the crystal field excitations of the V-sublattice and the rare earth ions, respectively. The data will be compared with previously obtained INS data of D. Senff on TbMnO{sub 3} and our INS data on DyMnO{sub 3} with the intention of uncovering information about the complex interplay between the magnetic moments of the rare earth ions its role in the formation of the multiferroic phase.
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    Investigations into the magnetic and crystal field excitations of the orthorhombically distorted perovskites RVO3 (R=Dy, Tb, Pr, Ce)
    (Australian Institute of Physics, 2013-02-06) Reynolds, NM; Rovillain, P; Danilkin, SA; Schmalzl, K; Reehuis, M; Miyasaka, S; Fujioka, F; Tokura, Y; Keimer, B; McIntyre, GJ; Ulrich, C
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    Investigations into the magnetic and crystal field excitations of the orthorhombically distorted perovskites TbVO3 and CeVO3
    (Australian Institute of Physics, 2018-01-30) O'Brien, J; Reynolds, N; Rovillain, P; Danilkin, SA; Schmalzl, K; Reehuis, M; Mole, RA; Miyasaka, S; Fujioka, F; Tokura, Y; Keimer, B; McIntyre, GJ; Ulrich, C
    Inelastic neutron scattering experiments have been performed on a series of vanadates, in particular TbVO3 and CeVO3, to categorise the crystal field and magnetic excitations. The vanadates possess a configuration with corner sharing, distorted VO6 octahedra (space group Pbnm) with a collinear C-type antiferromagnetic structure occurring below Néel temperatures of TN = 110 K and 124 K respectively. Data from neutron scattering experiments reveal a hitherto unobserved shift of crystal field excitation energy in TbVO3 and CeVO3. Point-charge model calculations have confirmed this shift by theoretically calculating the crystal field excitation spectrum. We propose that the mechanism behind the effect is the onset of local magnetism caused by the ordering of the vanadium sublattice at the magnetic phase transition. This magnetic exchange field from the vanadium ions polarises the spins of the rare-earth ions located at the centre of the unit cell. This results in a Zeeman-like splitting of crystal field energy levels. As a result, crystal field transition energies demonstrate a linear shift as a function of internal magnetic field strength.
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    Investigations of the magnetic and crystal field excitations in orthorhombically distorted perovskites RVO3 (R=Dy, Tb, Pr, Ce)
    (Australian Institute of Physics, 2017-01-31) O'Brien, J; Reynolds, NM; Mole, RA; Rovillain, P; Danilkin, SA; Schmalzl, K; Reehuis, M; Miyasaka, S; Fujioka, F; Tokura, Y; Keimer, B; McIntyre, GJ; Ulrich, C
    Inelastic neutron scattering experiments have been performed on a series of vanadates, in particular DyVO3, TbVO3, PrVO3, and CeVO3, to categorise the crystal field and magnetic excitations. The vanadates are isostructural to the multiferroic manganites TbMnO3 and DyMnO3, with corner sharing, Jahn-Teller distorted VO6 octahedra (orthorhombic space group Pbnm). However, they posses a collinear C-type antiferromagnetic structure, instead of an incommensurate spin arrangement as in the manganites. In the vanadates, the antiferromagnetic order sets in below Neel temperatures of TN = 110 K to 124 K [1-5]. Using inelastic neutron scattering on single crystals we were able to determine the crystal field spectrum and spin wave dispersion relations independently. In order to determine the nature of the crystal field excitations of these materials and in order to understand how the magnetic and crystal field excitations influence one another, we have theoretically calculated the crystal field excitation spectrum. The results are compared to the crystal field and spin wave excitations in the multiferroic maganites [6], in order to obtain a deeper understanding of the coupling mechanism between the rare earth elements and the transition metals in RVO3 and RMnO3, respectively.