Different helicity dependency of all-optical magnetization switching in GdFeCo films with optical interference layer

Abstract We observed helicity-dependent all-optical magnetization switching (HD-AOS) phenomena in GdFeCo films, which have equivalent magnetic properties but different optical properties due to optical interference layer thickness. Consequently, we found that these films have different properties of HD-AOS with the duality relation between magnetization direction and light helicity in light absorption, which generally means magnetic circular dichroism (MCD). Therefore, we also evaluated the effective absorption of the same GdFeCo samples which have similar intrinsic MCD by CW laser and intense femtosecond laser pulses. We confirmed that the contribution of this duality relation is much smaller in the absolute value of absorption. Furthermore, the magnitude and the sign of the duality relation change by the interference layer’s thickness. As a result, we concluded that the duality relation in HD-AOS is derived from the duality relation in absorption. Furthermore, its duality relation can be changed effectively using multiple interference effects.