Mn⁵⁵ nuclear magnetic resonance in antiferromagnetic RbMnF ₃

Abstract

The observation and study of the Mn55 nuclear magnetic resonance in antiferromagnetic RbMnF3 at low temperatures are reported. The direct detection is possible because of a large enhancement of the signal from one of the NMR modes in a low anisotropy antiferromagnet above the critical field for spin flopping. Large frequency pulling effects are observed, and found to be in excellent quantitative agreement with theory. The unpulled NMR frequency has been determined as 687 Mc/sec at 2°K, and the corresponding linewidth is 60 kc/sec. An anomalous increase in linewidth with decreasing field and temperature is described. © 1964 The American Institute of Physics.