Nuclear Magnetic Resonance Study on Pseudo One-Dimensional Antiferromagnet LiCuVO_4

概要

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The electronic and magnetic states of a pseudo one-dimensional (ID) antiferromagnet LiCuVO_4 (T_N=3.3K), which consists of distorted CuO_6 linear chains, have been investigated microscopically with nuclear magnetic resonance measurements. The characteristic of the ID antiferromagnetic (AF) spin=1/2 chains appears in a broad extremum of the resonance shift K for each of^<65>Cu, ^<51>V and ^7Li at the temperatures around T_M=28K, which can reasonably be compared with the Bonner-Fisher-type behavior of the susceptibility X. From the linear dependence of K on X, the hyperfine field for each of^<65>Cu, ^<51>V and ^7Li is estimated as ∿20, 5.6 and -0.25kOe/μB, respectively, indicating that the magnetism originates from Cu^<2+> ions on the octahedral B sites. The nuclear spin-lattice relaxation rate T^<-1>_1 of^<51>V on the tetrahedral A sites has somewhat complex temperature dependence, which can not simply be explained by the scaling theories for the standard AF spin=1/2 chain. A broad T^<-1>_1 maximum observed around 80K and an upturn below ∿15K are ascribed to the development of ID and 2D or 3D AF short-range orderings at rather high temperatures well above JM and TN, respectively.
社団法人日本物理学会の論文
2002-01-15