Magneto-optical observation of a magnetically induced « domain spin-flop » in a cubic antiferromagnet : KNiF3

Abstract

We have observed a large change in the field dependence of the magneto-optical spectra of cubic KNiF3 at a low magnetic field. This phenomenon, which is being reported for the first time, is compared to the well-known spin-flop occurring in uniaxial antiferromagnets. Spectroscopic calculations allow us to attribute the magnetic circular dichroism signals that have been observed below and above the critical field, to an antiferromagnetic and a spin-flop phase. We verify that in a cubic antiferromagnet, the reversible movement of domain twin-walls occurs at a lower magnetic field than the rotation of the spins inside a single domain