Magnetic interface polarization of the La-5d states in Fe/LaH x multilayers

For rare-earth (RE)-hydrides (REHx), a metal-to-insulator transition is observed if the hydrogen concentration is increased from the dihydride (x=2) towards the trihydride (x=3). This transition provides an object for studies of the magnetic interface polarization in layered ferromagnet/insulator structures. For different samples with a fixed Fe and varied LaHx sublayer thickness tLaHx ([15 A Fe/tA LaHx]xn), the H concentration x in the LaHx sublayer is gradually increased in the experiment. Starting from the as prepared dihydride REH2-δ, the modification of the magnetic polarization of the La-5d states at the Fe/Lax interface is studied across the transition by magnetic circular dichroism measurements at the La-L2 and L3 edges. The experiments reveal an induced magnetic polarization of the La-5d hole states on a length scale of 9 A that is independent of the altered electronic structure of the La-5d states.