Browsing by Author "Hayashida, S"
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- ItemMagnetic order in frustrated Kagome-Triangular lattice antiferromagnet NaBa2Mn3F11(American Physical Society, 2017-03) Hayashida, S; Ishikawa, H; Okamoto, Y; Okubo, T; Hiroi, Z; Avdeev, M; Manuel, P; Hagihala, M; Soda, M; Masuda, TWe performed powder neutron diffraction experiments on NaBa2Mn3F11 [1], a model compound of \textit{Kagome-Triangular} lattice where three of six next-nearest neighbor interactions are non-negligible. More than 10 magnetic Bragg peaks are clearly observed below T= 2 K, meaning that the ground state is a magnetically ordered state. From indexing the magnetic Bragg peaks, magnetic propagation vector of \textbf{\textit{q}}0= (0, 0, 0) and two incommensurate vectors which are close to (1/3, 1/3, 0) are identified. Combination of representation analysis and Rietveld refinement reveals that the propagation vector of \textbf{\textit{q}}0 exhibits the 120º structure in the \textit{ab}-plane. Our calculation of the ground state suggests that the non-negligible magnetic dipolar interaction is responsible for the determined 120º structure in NaBa2Mn3F11. © 2021 American Physical Society
- ItemMagnetic order in the chemically substituted frustrated antiferromagnet CsCrF 4(American Physical Society, 2020-11-24) Hayashida, S; Hagihala, M; Avdeev, M; Miura, Y; Manaka, H; Masuda, TThe effect of chemical substitution on the ground state of the geometrically frustrated antiferromagnet CsCrF4 has been investigated through a neutron powder diffraction experiment. Magnetic Fe-substituted CsCr0.94Fe0.06F4 and nonmagnetic Al-substituted CsCr0.98Al0.02F4 samples are measured, and magnetic Bragg peaks are clearly observed in both samples. Magnetic structure analysis revealed a 120∘ structure having a magnetic propagation vector kmag=(0,0,1/2) in CsCr0.94Fe0.06F4. For CsCr0.98Al0.02F4, a quasi- 120∘ structure having kmag=(1/2,0,1/2) is formed. It is notable that the identified magnetic structure in CsCr 0.94Fe0.06F4 belongs to a different phase of ground states from those in CsCr0.98Al0.02F4 and the parent CsCrF4. These results suggest that the Fe substitution strongly influences the ground state of CsCrF4.©2020 American Physical Society
- ItemMagnetic order in the rare-earth ferroborate CeFe3(BO3)4(American Physical Society, 2018-12-04) Hayashida, S; Asai, S; Kato, D; Hasegawa, S; Avdeev, M; Cao, H; Masuda, TWe have studied the magnetic order of the rare-earth ferroborate CeFe3(BO3)4 through the thermodynamic and the neutron diffraction measurements. The heat capacity and the magnetic susceptibility revealed antiferromagnetic magnetic ordering at 29 K. In the neutron powder diffraction data, we observed the magnetic Bragg peaks indexed by the commensurate (CM) propagation vector kCM=(0,0,32) and the incommensurate (ICM) vector kICM=(0,0,32+δ). The incommensurability δ increases with decreasing the temperature, and is evaluated to be 0.04556(16) at 3.7 K. Magnetic structure analysis reveals that the magnetic moments aligning in the ab plane form the collinear antiferromagnetic structure having kCM and helical structure having kICM. Detailed measurements of the magnetic susceptibility exhibit an additional anomaly at 27 K. Furthermore, the temperature dependence of the neutron diffraction profile on the single-crystal sample shows that the ICM and CM ordering occurs at 29 and 26 K, respectively. These results suggest a phase separation state between the collinear and helical structures. The multiferroicity of CeFe3(BO3)4 is discussed on the basis of the determined magnetic structure. ©2018 American Physical Society
- ItemMagnetic state selected by magnetic dipole interaction in the kagome antiferromagnet NaBa2Mn3F11(American Physical Society, 2018-02-12) Hayashida, S; Ishikawa, H; Okamoto, Y; Okubo, T; Hiroi, Z; Avdeev, M; Manuel, P; Hagihala, M; Soda, M; Masuda, TWe haved studied the ground state of the classical kagome antiferromagnet NaBa2Mn3F11. Strong magnetic Bragg peaks observed for d spacings shorter than 6.0 Å were indexed by the propagation vector of k0=(0,0,0). Additional peaks with weak intensities in the d-spacing range above 8.0 Å were indexed by the incommensurate vector of k1=[0.3209(2),0.3209(2),0] and k2=[0.3338(4),0.3338(4),0]. Magnetic structure analysis unveils a 120∘ structure with the tail-chase geometry having k0 modulated by the incommensurate vector. A classical calculation of the Heisenberg kagome antiferromagnet with antiferromagnetic second-neighbor interaction, for which the ground state a k0120∘ degenerated structure, reveals that the magnetic dipole-dipole (MDD) interaction including up to the fourth neighbor terms selects the tail-chase structure. The observed modulation of the tail-chase structure is attributed to a small perturbation such as the long-range MDD interaction or the interlayer interaction. ©2018 American Physical Society
- ItemMagnetic states of coupled spin tubes with frustrated geometry in CsCrF 4(Nature Publishing Group, 2019-04-23) Hagihala, M; Hayashida, S; Avdeev, M; Manaka, H; Kikuchi, H; Masuda, TWhen a theoretical model is realized in nature, small perturbation terms play important roles in the selection of the ground state in geometrically frustrated magnets. In case of a triangular spin tube, the two-dimensional network of the inter-tube interaction forms characteristic lattices. Among them Kagome-Triangular (KT) lattice is known to exhibit an enriched phase diagram including various types of non-trivial structures: non-coplanar cuboc structure, coplanar 120° structure with the two-dimensional propagation vector of k2D = (0, 0), 3–√×3–√ structure with k2D = (1/3, 1/3), and incommensurate structure. We investigate the magnetic state in the model material CsCrF4 by using neutron diffraction technique. Combination of representation analysis and Rietveld refinement reveals that a very rare structure, i.e., a quasi-120° structure with k2D = (1/2, 0), is realized at the base temperature. The classical calculation of the phase diagram elucidates that CsCrF4 is the first experimental realization of the KT lattice having ferromagnetic Kagome bond. A single-ion anisotropy and Dzyaloshinskii-Moriya interaction play key roles in the selection of the ground state. Furthermore, a successive phase transition having an intermediate state represented by k2D = (1/3, 1/3) is observed. The intermediate state is a partially ordered 120° structure which is induced by thermal fluctuation. © 2019, The Author(s)
- ItemMagnetic structure and dielectric state in the multiferroic Ca2CoSi2O7(The Physical Society of Japan, 2017-05-10) Soda, M; Hayashida, S; Yoshida, T; Akaki, M.; Hagiwara, M; Avdeev, M; Zaharko, O; Masuda, TThe magnetic structure of the multiferroic Ca2CoSi2O7 was determined by neutron diffraction techniques. A combination of experiments on polycrystalline and single-crystal samples revealed a collinear antiferromagnetic structure with the easy axis along the 〈100〉 directions. The dielectric state is discussed in the framework of the spin-dependent d–p hybridization mechanism, leading to the realization of the antiferroelectric structure. The origin of the magnetic anisotropy is discussed in comparison with that of the isostructural Ba2CoGe2O7. ©2017 The Physical Society of Japan