Origin of magnetic anisotropy, role of induced magnetic moment, and all-optical magnetization switching for Co100−xGdx/Pt multilayers

The combination of Co, Gd, and Pt materials is a representative with perpendicular magnetic anisotropy (PMA) for the all-optical switching (AOS), which provides a promising route for ultrafast magnetization manipulation. This paper shows that the PMA of Co100−xGdx/Pt multilayers mainly originates not from the bulk property of ferrimagnetic Co100−xGdx but from the interface magnetic anisotropy between the Co100−xGdx and Pt layers. In addition, the contribution of magnetic moment induced in Pt becomes remarkable, which modulates the compensation temperature for the samples with thin Co100−xGdx layers. The Co100−xGdx/Pt multilayers exhibited the all-optical helicity-independent switching in a wide range of Gd concentrations, and the maximum AOS probability was achieved near the compensation composition. We discuss the correlation between the magnetic properties and the AOS probability for the Co100−xGdx/Pt multilayers. The AOS showed clear thickness dependence, which was attributable to the remarkable contribution of induced moment. Our findings are beneficial not only for understanding the mechanism of AOS but also for designing spintronic devices using ferrimagnets.