Indirect Observation of Antiferromagnetic Domains by Linear Magnetostriction

This paper reports the annealing and switching of purely antiferromagnetic domains in αFe2O3 as identified by measurements of the coefficients of linear magnetostriction in complete agreement with the predictions of magnetic symmetry. The domain state was found to follow a hysteresis reversal loop caused probably by domain pinning centers within the crystal. The linear magnetostriction coefficients were virtually independent of temperature in the range 77° to 220°K. Magnetostriction also revealed a field-induced reduction of the magnetic transition temperature, this being related to the relative thermodynamic potentials of the two phases. This reduction explains the unusually large measured strains close to the transition in terms of the volume changes resulting from the magnetic transition.