Dynamics of the Antiferromagnetic Spin-Flop Transition

Abstract

The critical magnetic field producing spin flop in many antiferromagnets is too small to soften a three-dimensional magnon, i.e., to remove the energy barrier between the equal-energy phases. The barrier can be bypassed, however, via the softening of surface magnons in a smaller field, forming two-dimensional surface-spin-flop states, which broaden with increasing field and which catastrophically spread inward across the three-dimensional material as the critical field is approached.