Depth-resolved electronic structure of a BiFeO₃/La_0.7Sr_0.3MnO₃ superlattice investigated by standing-wave hard X-ray photoemission spectroscopy (SW-HXPS)

Studies of artificially designed interfaces of transition metal oxide heterostructures enable opportunities to engineer new stable phases of matter, leading to novel complex devices. However, it is a challenge to identify the features in the electronic structure that induce these emergent interfacial phenomena. Here we have studied a prototypical ferroelectric/ferromagnetic interface between two perovskite oxides, BiFeO₃ and La_0.7Sr_0.3MnO₃, by Bragg-reflection standing-wave hard X-ray photoemission spectroscopy (SW-HXPS). The superior depth precision of the SW-HXPS provides information on interfacial and “bulk” signals, and it allows us to identify the character of the interfacial features in the electronic structure in correlation with the detailed depth information on chemical states.