⁵⁵Mn NMR in an Antiferromagnetic RbMnCl₃

Abstract

⁵⁵Mn NMR signals in RbMnCl₃ has been observed at 624.2 MHz and 585.7 MHz at 4.2 K. With decreasing the temperature, these frequencies decreased with nearly 1⁄T. The temperature dependence is reproduced in terms of the four sublattice model, taking the strong hyperfine interaction and the unequal electronic magnetization on the two inequivalent Mn²⁺ sites into consideration Corresponding to two Mn²⁺ sites, there are two exchange interactions with constants of J₁ and J₂. From the ratio between two electronic magnetizations obtained from the analysis of the resonance frequencies, J₂⁄J₁ has been evaluated to be 0.3–0.4 by use of the results calculated on the basis of the pair and lone spin model.