Browsing by Author "Watanabe, I"

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    Muon spin relaxation and neutron diffraction studies of cluster-glass states in Sr1−xLaxRuO3
    (The Physical Society of Japan, 2016-04-04) Kawasaki, I; Fujimura, K; Watanabe, I; Avdeev, M; Tenya, K; Yokoyama, M
    To clarify the magnetic properties of cluster-glass states in Sr1−xLaxRuO3 (0.3 ≤ x ≤ 0.5), we report herein the results of muon spin relaxation (μSR) and neutron powder diffraction measurements. The μSR experiments showed that magnetic clusters start developing well above the peak temperature T* in the ac susceptibility. The volume fraction of the magnetically ordered region increases continuously with decreasing temperature, showing no anomaly at T*, and reaches nearly 100% at the lowest temperature. The temperature variation of the volume fraction is essentially independent of the La concentration in the x range presently investigated, although the dc magnetization is significantly suppressed with increasing x. Neutron powder diffraction experiments revealed that the ground state for x = 0.3 is a long-range ferromagnetic ordered state. These results indicate that, with decreasing temperature, cluster-glass states in Sr1−xLaxRuO3 gradually develop into long-range ferromagnetic ordered states with decreasing temperature, and that the magnetic ordering process differs strikingly from that expected for a conventional second-order ferromagnetic transition. ©2016 The Physical Society of Japan
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    Spin dynamics and magnetic ordering in the quasi-one-dimensional S=12 antiferromagnet Na2CuSO4Cl2
    (American Physical Society (APS), 2020-01-01) Fujihala, M; Mitsuda, S; Mole, RA; Yu, DH; Watanabe, I; Yano, S; Kuwai, T; Sagayama, H; Kouchi, T; Kamebuchi, H; Tadokoro, M
    The S=12 quasi-one-dimensional antiferromagnet K2CuSO4X2(X=Cl, Br) exhibits peculiar Dzyaloshinskii-Moriya (DM) interactions that are uniform along its spin chains and antiparallel with respect to neighboring chains. This feature has received much attention recently because it leads to spin frustration, however, the spin dynamics around TN and magnetic structure have not been reported. Here we report magnetic behaviors of Na2CuSO4Cl2. The orthorhombic crystal structure of Na2CuSO4Cl2, which is identical to K2CuSO4X2, was verified. The results of the thermodynamic measurements suggest that this compound has moderately strong intra- and interchain interaction for investigation of the spin state around TN. The inelastic neutron scattering and muon spin relaxation and rotation measurements reveal the presence of a two-spinon continuum, and below TN, the long-range order develops. However, the obtained critical exponent is β=0.18, which is not indicative of a three-dimensional magnetic system; instead, one-dimensional (1D) spin correlation likely affects the formation of magnetic ordering in Na2CuSO4Cl2. There is a possibility that Na2CuSO4Cl2 is a model compound for investigation of DM-induced frustration effects in a 1D quantum spin system. ©2024 American Physical Society. All rights reserved.