Interface properties of magnetic tunnel junctionLa0.7Sr0.3MnO3/SrTiO3superlattices studied by standing-wave excited photoemission spectroscopy

The chemical and electronic-structure profiles of magnetic tunnel junction (MTJ) La0.7Sr0.3MnO3/SrTiO3 (LSMO/STO) superlattices have been quantitatively determined via soft and hard x-ray standing-wave excited photoemission, x-ray absorption and x-ray reflectivity, in conjunction with x-ray optical and core-hole multiplet theoretical modeling. Epitaxial superlattice samples consisting of 48 and 120 bilayers of LSMO and STO, each nominally four unit cells thick, and still exhibiting LSMO ferromagnetism, were studied. By varying the incidence angle around the superlattice Bragg condition, the standing wave was moved vertically through the interfaces. By comparing experiment to x-ray optical c…