Browsing by Author "Yano, S"

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    The cold-neutron triple-axis spectrometer SIKA at OPAL
    (International Conference on Neutron Scattering, 2017-07-12) Deng, G; Yano, S; Wu, CM; Peng, JC; Imamovic, E; Vorderwisch, P; Li, WH; Gardner, JS
    SIKA is a high-flux cold-neutron triple-axis spectrometer built on the cold source CG4 of the 20MW Open Pool Australian Light-water (OPAL) reactor at Australian Nuclear Science and Technology Organization (ANSTO) by Taiwan.[1] As a state-of-the-art triple-axis spectrometer, SIKA is equipped with a large double-focusing pyrolytic graphite (PG) monochromator, a multiblade PG analyser and a multi-detector system. The design, functions, and capabilities of SIKA are presented. The spin wave excitation of MnF2, the phonon dispersion of thermoelectric material SeSn,[2] the spin dynamics of spin glass system (Ni0.40Mn0.60)TiO3[3] and other experimental data from SIKA are demonstrated as examples of SIKA’s capabilities and performance.
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    Relief of spin frustration through magnetic anisotropy in the quasi-one-dimensional 𝑆= 1/2 antiferromagnet Na2⁢CuSO4⁢Cl2
    (American Physical Society (APS), 2022-03-29) Fujihala, M; Sakuma, Y; Mitsuda, S; Nakao, A; Munakata, K; Mole, RA; Yano, S; Yu, DH; Takehana, K; Imanaka, Y; Akaki, M; Okubo, S; Ohta, H
    We report the magnetic structure and anisotropy of the quasi-one-dimensional S=12 antiferromagnet Na2CuSO4Cl2 obtained by single-crystal neutron scattering, electron spin resonance (ESR), and magnetization measurements, following an earlier study of its dynamics [M. Fujihala, Phys. Rev. B 101, 024410 (2020)10.1103/PhysRevB.101.024410]. A Néel-Type spin structure is formed within the chain of this compound, where the spins point along the b axis, and ESR data indicate an antisymmetric exchange with a uniform Dzyaloshinskii-Moriya (DM) vector pointing along the b axis. The anisotropy g factor and magnetic structure are strong indicators of magnetic anisotropy originating from a symmetric anisotropic exchange interaction and/or a magnetic dipole interaction. These results suggest that these terms of the anisotropic spin Hamiltonian counteract the effect of the DM interaction and stabilize the Néel-Type structure in Na2CuSO4Cl2. ©2022 American Physical Society.
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    Weak trimerization in the frustrated two-dimensional triangular Heisenberg antiferromagnet LuyY1−yMnO3
    (American Physical Society, 2023-06-02) Yano, S; Wang, CW; Gardner, JS; Chen, WT; Iida, K; Mole, RA; Louca, D
    To understand the 2D triangular Heisenberg antiferromagnetic system, we investigated the magnetic structures and the dynamics of LuyY1-yMnO3 in detail. The substitutions are adjusted to the Mn atomic position close to xMn=13. The neutron powder diffraction data claims that the magnetic structure of LuyY1-yMnO3 is described as a mixture of Γ3 (P63′cm′) and Γ4 (P63′c′m) at the xMn position for y=0.15, 0.30, and 0.45. The ratio of Γ3 and Γ4 depends on temperature and composition and the fraction of Γ3 increases upon cooling, while no clear trimerization was observed at the xMn position. We estimated exchange parameters from the analysis of the low-energy part of the spin waves. The results showed a weak trimerization effect on cooling because the nearest-neighbor exchange interaction is slightly enhanced. The temperature dependence of the spin-wave dispersion around the Γ point shows that the spin gap closes with increasing temperature because the exchange interactions in the nearest Mn-Mn neighbor become smaller. Gapless diffusive magnetic excitation from a Mn triangular lattice has been observed in a wide range in Q and E space of LuyY1-yMnO3. We found that Lu0.3Y0.7MnO3 could be an ideal case to investigate the trimerization, frustrated magnetism, and magnetoelastic coupling often observed in two-dimensional triangular lattice Heisenberg antiferromagnet systems. ©2023 American Physical Society