Magnetic second harmonic study of Cr/Fe and Ag/Fe buried interfaces

The magnetic properties of Ag/Fe/MgO and Cr/Fe/MgO multilayers have been studied in air by both linear (MOKE) and non-linear (MSHG) magneto-optics. Thanks to the different probing sensitivities of the two techniques, film and interface properties can be separately measured. In the Ag/Fe/MgO case, coercive field values measured with linear and non-linear optics are very similar, indicating that a sharp interface is formed and that the presence of silver on top of iron does not alter its magnetic properties. The values of coercive field measured with MOKE for the Cr/Fe/MgO multilayer differ significantly with respect to the Ag case, and furthermore different coercive fields have been measured on this system with MOKE and MSHG. We ascribe the observed effects to spin frustration caused the layered antiferromagnetic Cr spin structure along with the presence of steps at the Cr/Fe interface.