Hyperfine Field and51V Nuclear Relaxation in the Paramagnetic State of the Triangular Lattice Antiferromagnet VX2(X=Cl, Br and I)

The microscopic magnetic properties of the paramagnetic state in the triangular Heisenberg antiferromagnet VX 2 (X=Cl, Br and I) have been investigated by using the NMR technique. From the 51 V shift vs the magnetic susceptibility plot the hyperfine coupling constant due to the d-spin core polarization effect is determined to be -95 ±2, -79 ±2 and -69 ±2 kOe/ µ B for VCl 2 , VBr 2 and VI 2 , respectively. Also it has been revealed that the high temperature value of the 51 V nuclear spin-lattice relaxation rate is explained from the Guassian model for the auto-correlation function of the spin fluctuations.