V-51-NMR study on the S=1/2 square lattice antiferromagnet K2V3O8

Article

关键词: NUCLEAR MAGNETIC-RELAXATION;    WEAK FERROMAGNETISM;   

DOI  :  10.1103/PhysRevB.100.054406

来源: SCIE

【 摘 要 】

Static and dynamic properties of the quasi-two-dimensional antiferromagnet K2V3O8 have been investigated by V-51-NMR experiments on nonmagnetic V5+ sites. Above the structural transition temperature T-S = 115 K, NMR spectra are fully compatible with the P4bm space-group symmetry. The formation of superstructure below T-S causes splitting of the NMR lines, which get broadened at lower temperatures so that individual peaks are not well resolved. Evolution of NMR spectra with magnetic field along the c axis below the magnetic transition temperature T-N similar to 4 K is qualitatively consistent with a simple Neel order and a spin-flop transition. However, a broad feature of the spectra does not rule out possible incommensurate spin structure. The spin-lattice relaxation rate 1/T-1 below T-N shows huge enhancement for a certain range of magnetic field, which is independent of temperature and attributed to cross relaxation due to anomalously large nuclear spin-spin coupling between V5+ and magnetic V4+ sites. The results indicate strong gapless spin fluctuations, which could arise from incommensurate orders or complex spin textures.

【 授权许可】

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