Magnetodielectric effect via a noncollinear-to-collinear spin reorientation in rare-earth iron garnets

Abstract

The discovery of ferroelectrics induced by peculiar magnetic structures brought about extensive theoretical and experimental studies. The key driving force for these magnetic ferroelectrics appears to lie in the inverse Dzyaloshinskii-Moriya (DM) interaction in magnets with long-wavelength ``noncollinear'' spin structures. In this Brief Report, we report the magnetodielectric effect in dysprosium iron garnet which has a noncollinear spin structure within a single unit cell, through the same DM interaction. The distinct effects of magnetism on the lattice are also demonstrated by the unprecedented magnetostriction with a negative Poisson ratio. We attribute the observed magnetodielectric effects and the huge magnetostriction to the magnetic-field-induced spin reorientation from noncollinear to collinear, which possibly weakens the proposed antiferroelectric-type lattice distortion. Our results suggest an additional class of magnetodielectrics and enrich the theoretical understanding of phenomena related to peculiar magnetic structures.