Spin density wave as a superposition of two magnetic states of opposite chirality and its implications

Abstract

A magnetic solid with weak spin frustration tends to adopt a noncollinear magnetic structure such as cycloidal structure below a certain temperature and a spin density wave (SDW) slightly above this temperature. The causes for these observa-tions were explored by studying the magnetic structures of BaYFeO4, which undergoes an SDW and a cycloidal phase transi-tion below 48 and 36 K, respectively, in terms of density func-tional theory calculations. We show that an SDW structure aris-es from a superposition of two magnetic states of opposite chi-rality, an SDW state precedes a chiral magnetic state due to the lattice relaxation, and whether an SDW is transversal or longitudinal is governed by the magnetic anisotropy of magnetic ions.