Direct probe of interdiffusion effects on the induced V spin polarization at Fe/V interfaces

X-ray magnetic circular dichroic measurements have been performed at room temperature at the V L2,3 edges on Fe/V/Fe(110) trilayers to determine the induced V spin polarization. Contrary to similar studies on magnetic multilayers, the sample preparation and characterization were performed thoroughly in situ under ultrahigh vacuum conditions. This allowed us to modify the interfaces by tuning the deposition temperature and to probe directly the influence of interface quality on the induced V moments. The magnitude of the induced V moment increased by about a factor of 2 upon changing the deposition temperature from 300 K to 600 K. Comparison with ab initio calculations and with spectra of FeV alloys suggests that alloying at the interface results in the formation of large induced V moments.