Browsing by Author "Hagihala, M"
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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 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-field-induced instability of the cooperative paramagnetic state in ZnxCo(4-x)(OD)6Cl2(American Physcical Society, 2012-05-29) Dissanayake, SE; Chan, C; Ji, S; Lee, J; Qiu, Y; Rule, KC; Lake, B; Green, MA; Hagihala, M; Zheng, XG; Ng, TK; Lee, SHUsing elastic and inelastic neutron scattering techniques with and without application of an external magnetic field H, the magnetic ground states of ZnxCo(4-x)(OD)6Cl2 (x = 0,1) were studied. Our results show that for x = 0, the ground state is a magnetic long-range ordered (LRO) state where each tetrahedron forms an "umbrella"-type structure. On the other hand, for x = 1, no static ordering was observed down to 1.5 K, which resembles the behavior found in the isostructural quantum system ZnxCo(4-x)(OD)6Cl2. When H field is applied, however, the x = 1 system develops the same LRO state as x = 0. This indicates that the x = 1 disordered state is in the vicinity of the x = 0 ordered state. © 2012, American Physical Society.
- ItemNeutron scattering study of magnetic structure in triangle spin tube CsCrF4(American Physical Society, 2016-03) Hagihala, M; Avdeev, M; Manaka, H; Masuda, TTriangle spin tube viewed from tube direction is topologically equivalent to kagomé lattice. The rung (J1) and inter-tube (J2) interactions on triangle spin tube correspond respectively to the next nearest neighbor and the nearest neighbor interactions on kagomé lattice. In the case of J1>0 (Antiferromagnetic) and J1>>|J2|, the ground state is q=0,120∘ structure with J2>0 or Cuboc state that represented multi-q (q=2π(1/2 0) and two symmetric-equivalent vectors) with J2<0 [1]. CsCrF4 is a perfect triangle spin tube material with antiferromagnetic intra-tube and rung interactions [2]. Neutron diffraction measurement revealed magnetic long-range order at T=1.5 K. Contrary to the expectation, the magnetic structure was determined q=2π(1/2 0 1/2), 120∘ structure by Rietveld refinement. We also confirmed that this structure was stabilized by Dzyaloshinskii -Moriya interaction and small anisotropy that obeyed the three-fold symmetry at Cr sites by calculation. © 2021 American Physical Society