Magnetostriction of antiferromagnetic MnF2 in a strong field
Аннотация
The magnetostriction of a uniaxial MnF2 antiferromagnet is measured at 10°K in a field up to 150 kOe. A jump in the deformation along the axis of crystal symmetry and subsequent quadratic growth are observed in a magnetic field (Hc = 91.7 kOe) parallel to this axis. The deformation grows quadratically in H in a perpendicular field. The jumplike change in the crystal dimensions at H = Hc agrees with the concept of a sublattice-flipped phase transition which occurs in this field. The magnetostriction of MnF2 is explained by the dependence on the anisotropy energy and the exchange energy whose contributions are separated. The experimental results are in good agreement with estimates of the magnitudes of these contributions, obtained on the basis of magnetic dipole and indirect exchange interactions.