Resonance Behaviour in Canted Antiferromagnet KMnF₃

Abstract

The magnetic property of the crystal KMnF 3 was studied by the electron spin resonance method using several microwave frequencies. As the temperature was reduced from the Néel temperature of 88.3 K the resonance points shifted toward the low field. These lines, however, disappeared below 81.5 K and the other lines appeared. The field induced canted phase in the intermediate-temperature range is different from the low-temperature canted phase. Though the angular dependence of the spectra at 82.5 K observed by using the lowest frequency can be explained by the simple uniaxial antiferromagnetic resonance theory, the results at 24 GHz can not be explained by this theory. Tentatively, they are compared with the theory which assumes an antisymmetric exchange interaction with the Dzyaloshinsky-Moriya vector parallel to the easy axis. The agreement between the experiment and the theory seems to be fairly good.