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阿部 伸行*; 塩澤 俊介*; 松浦 慧介*; 佐賀山 基*; 中尾 朗子*; 大原 高志; 徳永 祐介*; 有馬 孝尚*
Physical Review B, 101(18), p.180407_1 - 180407_5, 2020/05
被引用回数:2 パーセンタイル:12.28(Materials Science, Multidisciplinary)The correlation between magnetism and electric polarization in a chiral insulating magnet BaFeOCl has been investigated. The temperature dependence of magnetic susceptibility shows an anomaly at 564 K, suggesting the onset of antiferromagnetic order of Fe moments. Electric polarization appears in a magnetic field below TN due to the spin-direction-dependent metal-ligand hybridization. The direction of the electric polarization can be controlled in three-dimensional space by changing the direction of an external magnetic field. This compound also shows an antiferromagnetic-to-weak-ferromagnetic transition accompanied by a structural phase transition at 140 K.
松浦 慧介*; 佐賀山 基*; 上原 周*; 新居 陽一*; 梶本 亮一; 蒲沢 和也*; 池内 和彦*; Ji, S.*; 阿部 伸行*; 有馬 孝尚*
Physica B; Condensed Matter, 536, p.372 - 376, 2018/05
被引用回数:2 パーセンタイル:10.13(Physics, Condensed Matter)We have investigated the temperature dependence of magnetic dynamics in a spinel-type vanadium oxide MnVO by inelastic neutron scattering. The scattering intensity of excitation around 20 meV disappears in the collinear intermediate-temperature cubic-ferrimagnetic phase, which reveals that this excitation should be peculiar to the orbital ordered phase. We have found a weakly dispersive mode emergent from a non-integer wavevector at 56 K, which lies in the cubic-ferrimagnetic phase between non-coplanar ferrimagnetic and paramagnetic phases. This indicates that the probable presence of an incommensurate instability in the simple collinear structure.
松浦 慧介*; 佐賀山 基*; 上原 周*; 新居 陽一*; 梶本 亮一; 蒲沢 和也*; 池内 和彦*; Ji, S.*; 阿部 伸行*; 有馬 孝尚*
Physical Review Letters, 119(1), p.017201_1 - 017201_6, 2017/07
被引用回数:14 パーセンタイル:67.59(Physics, Multidisciplinary)We investigate the magnetic dynamics in the spinel-type vanadium oxide MnVO. Inelastic neutron scattering around 10 meV and a Heisenberg model analysis have revealed that V spin-wave modes exist at a lower-energy region than previously reported. The scattering around 20 meV cannot be reproduced with the spin-wave analysis. We propose that this scattering could originate from the spin-orbital coupled excitation. This scattering is most likely attributable to V spin-wave modes, entangled with the orbital hybridization between orbitals.
Khanh, N. D.*; 阿部 伸行*; 佐賀山 基*; 中尾 朗子*; 花島 隆泰*; 鬼柳 亮嗣; 徳永 祐介*; 有馬 孝尚*
Physical Review B, 93(7), p.075117_1 - 075117_6, 2016/02
被引用回数:101 パーセンタイル:95.22(Materials Science, Multidisciplinary)The magnetic structure and magnetoelectric effect have been investigated for single crystals of the antiferromagnet CoNbO. Single-crystal neutron diffraction and magnetic susceptibility measurement have revealed that the magnetic structure is different from a collinear arrangement with spin parallel to the trigonal axis as proposed previously. Co magnetic moments are found to be almost lying in the basal plane, which lowers the magnetic symmetry to with the propagation vector = 0. Associated with the magnetic phase transition, a sharp anomaly in the dielectric constant and displacement current indicate the appearance of the magnetoelectric below Neel temperature TN with a large coupling constant up to 30 ps/m. The existence of off-diagonal components in a magnetoelectric tensor indicate the formation of ferrotoroidic order in CoNbO. Such a magnetoelectric effect can be ascribed to the reduction of symmetry caused by simple antiferromagnetic order in a honeycomb network.
福永 守*; 坂本 勇馬*; 木村 宏之*; 野田 幸男*; 阿部 伸行*; 谷口 耕治*; 有馬 孝尚*; 脇本 秀一; 武田 全康; 加倉井 和久; et al.
Physical Review Letters, 103(7), p.077204_1 - 077204_4, 2009/08
被引用回数:50 パーセンタイル:86.29(Physics, Multidisciplinary)We discovered a reversible electric polarization flop from the axis () to the axis () in multiferroic TmMnO below 5 K by applying a magnetic field of approximately 0.5 T along the axis. This phenomenon is the first example of the rare-earth () compound MnO. This magnetic-field-induced polarization flop corresponds to a magnetic phase transition from one incommensurate magnetic (ICM) phase to another ICM phase, which is equivalent to an ICM phase above 5 K under no magnetic field. The spin chirality in the plane, which was observed in the phase by polarized neutron diffraction, disappeared in the ICM phase. This indicates that the polarization in the ICM phases of TmMnO was induced by an type interaction.