1H NMR study of the spin dynamics in layered perovskite paramagnets [RNH3]2CuCl4 (R = C6H5, p-nitro-C6H5, C6H5CH2CH2)

The spin dynamics in [RNH3]2CuCl4 (R = C6H5, p-nitro-C6H5, C6H5CH2CH2) were investigated by 1H NMR through the frequency dependence of 1H spin-lattice relaxation rates (T1−1) from 12 to 400 MHz. It was found that the spin dynamics are governed by two-dimensional diffusive behavior and are limited by cut-off to the spin correlation in the low-frequency region. The cut-off frequency clearly depended on the interlayer distance, suggesting that the cut-off to the spin correlation originates in the interlayer dipolar interaction.