Investigation of NMR in the quasi-one-dimensional antiferromagnetic CsMnBr3

Abstract

The NMR spectrum of the quasi-one-dimensional easy-plane antiferromagnet CsMnBr3 with a triangular magnetic structure has been studied. The measurements were performed in the decimeter microwave range in a special NMR spectrometer and in a wide range of magnetic fields at temperatures of 1.7 and 3.0 K. Three branches of the NMR spectrum were observed. One branch exhibits a very strong frequency-field dependence. This dependence can be explained, to a first approximation, by the existing theory of the interaction of the electronic and nuclear subsystems [E. A. Turov and M. P. Petrov, Nuclear Magnetic Resonance in Ferro-and Antiferromagnets, Halstead Press, N. Y., 1972]. To explain the behavior of the two other branches, a more complicated theoretical analysis is required. The observed shift of the NMR spectrum with increasing temperature also cannot be explained. The reduction of the spin moment of the magnetic ion Mn2+ due to magnetic fluctuations is determined to be 30%.