dr. Timo Kuschel: Investigations of the magnetic proximity effect in non-magnetic/ferromagnetic bilayers by x-ray resonant magnetic reflectivity for spin caloritronic applications

Platin is often used to detect spin currents in an adjacent magnetic film nowadays using the inverse spin Hall effect. But unfortunately, parasitic charge based effects can be induced due to spin polarization in Pt generated by the magnetic proximity effect, if Pt is adjacent to a ferromagnetic material. For example, in spin caloritronics the anomalous Nernst effect can contribute to the thermal generation of spin currents (spin Seebeck effect), when an out-of-plane temperature gradient is applied in magnetic thin films. We propose to use magnetooptic techniques like x-ray resonant magnetic reflectivity (XRMR) to investigate the spin polarization at the interface to a feromagnetic material to identify or exclude magnetic proximity effects in these nanostructures. XRMR is interface-sensitive and, therefore, mainly independent from the Pt thickness, which makes it preferable over standard x-ray magnetic circular dichroism techniques.
In my talk, I will present our spin Seebeck experiments in Pt/NiFe2O4 bilayers and introduce the interface-sensitive techique XRMR for the spin polarization detection.