Random-field induced memory effects in inhomogeneously diluted antiferromagnets K 2Ni xZn 1− xF 4

Abstract

Using neutron diffraction a random-field generated memory is observed in K 2Ni x Zn 1− x F 4 with x = 0.96, 0.85, and 0.75. The intensities and profiles of magnetic Bragg reflections are found to follow unique trajectories determined by switching the external magnetic field on and off while cooling. The effect, associated with a inhomogeneous spread in T N on a microscopic scale, is a direct manifestation of freezing in of multi-domain states at the ordering temperature.