Giant widening of interface magnetic layer in almost compensated iron garnet (2201.00134v1)

Abstract: A two-sublattice ferrimagnet undergoes a transition from a collinear to canted magnetic phase at magnetic field oriented along an easy magnetization direction. In this work, we study the transition by means of the magneto-optical Faraday effect in a thin film of compensated iron garnet (Lu${3-{\rm{x}}}$Bi${\rm{x}}$)(Fe${5-{\rm{y}}-{\rm{z}}}$Ga${\rm{y}}$Al${\rm{z}}$)O${12}$ grown on Gd$3$Ga$_5$O${12}$ substrate. In the immediate vicinity of the compensation temperature a precursor of the transition with a complex shape was observed. Using a special sample with variable thickness we demonstrate an interfacial origin of the precursor. Diffusion of gadolinium from the substrate into the film forms a thin intermixed layer with enhanced magnetization. It induces an extended inhomogeneous magnetic structure in the film. A two-step shape of the precursor appears due to an easy-plane anisotropy of the intermixed magnetic layer. We emphasize that an effective width of the inhomogeneous magnetization distribution in the film grows enormously while approaching the compensation temperature.