Spin-Wave Dispersion in KMnF3

Abstract
The spin‐wave dispersion curve of antiferromagnetic KMnF3 at 4.2°K has been measured by means of neutron inelastic scattering. With incident neutron energies of 105° and 165°K, propagation was observed out to the zone boundary in the pseudocubic (110) plane. Least‐squares fitting of the spin‐wave energies to an expression involving the nearest and next‐nearest‐neighbor exchange interactions J1 and J2 and an anisotropy field HA yielded the results J1/k=3.80°±0.04°K, J2/k=0.11°±0.02°K and HA=3.1±0.4 kOe.