Distribution of electronic reconstruction at the n-type LaAlO3/SrTiO3 interface revealed by hard x-ray photoemission spectroscopy

Abstract

We investigated the electronic reconstruction at the n-type LaAlO3/SrTiO3 interface with hard x-ray photoelectron spectroscopy (HAXPES) under grazing incidence. By exploiting the collapse of evanescent x-ray waves and the abrupt increase of x-ray absorption at the critical incidence angle, our HAXPES study reveals a 2% electronic reconstruction from Ti4+ to Ti3+ occurring near the interface. Such an electronic reconstruction also extends from the interface into SrTiO3 with a depth of about 48 angstrom (similar to 12 unit cells) and an estimated total charge transfer of similar to 0.24 electrons per two-dimensional unit cell. (C) 2011 American Institute of Physics. [doi:10.1063/1.3672099]