Inelastic Neutron Scattering Study on Anisotropic Exchange and Dzyaloshinsky–Moriya Interactions in the $S = 1/2$ Triangular Spin Cluster V3

概要

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Inelastic neutron scattering (INS) experiments have been performed on a V3 triangular spin cluster. At the base temperature ($T = 0.7$ K), the INS spectrum clearly exhibits a broad peak at $\hbar\omega = 0.8$ meV. The peak was ascribed to the superposition of four magnetic excitations from two $S_{\text{total}} = 1/2$ doublets to two $S_{\text{total}} = 3/2$ doublets. From the observed peak position, width, and intensity, we confirmed a model Hamiltonian comprising anisotropic exchange and Dzyaloshinsky–Moriya (DM) interactions, and estimated the Hamiltonian parameters as $J^{x} = J^{y} = -5.73$ K, $J^{z} = -6.83$ K, $D_{1,2}^{z} = 0.261$ K, and $D_{2,3}^{z} = D_{3,1}^{z} = 0.287$ K, where $J^{\alpha}$ is the $\alpha$-component of the exchange interactions and $D_{i, j}^{z}$ represents the $z$-component of the DM vector between the $i$-th and $ j$-th V4+ ions. The resulting model Hamiltonian successfully reproduced the half-step magnetization process reported earlier as well as magnetic susceptibility.
2009-11-15