title: Imaging the evolution of d states at a strontium titanate surface.
abstract: Oxide electronics is a promising alternative to the conventional silicon-based semiconductor technology, owing to the rich functionalities of oxide thin films and heterostructures. In contrast to the silicon surface, however, the electronic structure of the SrTiO3 surface, the most important substrate for oxide thin films growth, is not yet completely understood. Here we report on the electronic states of a reconstructed (001) surface of SrTiO3 determined in real space, with scanning tunneling microscopy/spectroscopy and density functional theory calculations. We found a remarkable energy dependence of the spectroscopic image: Theoretical analysis reveals that symmetry breaking at the surface lifts the degeneracy in the t2g state (dxy, dyz, and dzx) of Ti 3d orbitals, whose anisotropic spatial distribution leads to a sharp transition in the spectroscopic image as a function of energy. The knowledge obtained here could be used to gain further insights into emergent phenomena at the surfaces and interfaces with SrTiO3.
authors.affiliation: Advanced Institute for Materials Research (AIMR), Tohoku University , Sendai 980-8577, Japan.
authors.forename: Ikutaro
authors.initials: I
authors.lastname: Hamada
authors.forename: Ryota
authors.initials: R
authors.lastname: Shimizu
authors.forename: Takeo
authors.initials: T
authors.lastname: Ohsawa
authors.forename: Katsuya
authors.initials: K
authors.lastname: Iwaya
authors.forename: Tomihiro
authors.initials: T
authors.lastname: Hashizume
authors.forename: Masaru
authors.initials: M
authors.lastname: Tsukada
authors.forename: Kazuto
authors.initials: K
authors.lastname: Akagi
authors.forename: Taro
authors.initials: T
authors.lastname: Hitosugi