Formation of orbital-selective electron states in LaTiO3/SrTiO3superlattices

Abstract

The interface electronic structure of correlated LaTiO 3 /SrTiO 3 superlattices is investigated by means of the charge self-consistent combination of the local density approximation (LDA) to density functional theory with dynamical mean-field theory. Utilizing a pseudopotential technique together with a continuous-time quantum Monte Carlo approach, the resulting complex multiorbital electronic states are addressed in a coherent fashion beyond static mean field. General structural relaxations are taken into account on the LDA level and cooperate with the driving forces from strong electronic correlations. This alliance leads to a Ti(3d xy ) dominated low-energy quasiparticle peak and a lower Hubbard band in line with photoemission studies. Furthermore correlation effects close to the band-insulating bulk SrTiO 3 limit as well as the Mott-insulating bulk LaTiO 3 limit are studied via realistic single-layer embeddings.

Towards Mott design byδ-doping of strongly correlated titanates

“…But since our focus is on the challenging large-scale heterostructure problem, where such recent extensions are very expensive, we work in a minimal t g 2 -based correlation framework. In an initial study [10], the δ-doping of LTO with a single SrO layer was in part already investigated within DFT+DMFT. But there the inplane lattice constant a = b of bulk SrTiO 3 , a site-averaged DC as well as cubic t g 2 projections (i.e., not adapted to the local cf eigenbasis) were used.…”

“…As a specific realization thereof, the δ-doped oxide heterostructures [4][5][6][7] (i.e., introducing well-defined impurity monolayers into a given host oxide compound) recently emerged as a canonical method to create challenging electronic states from experimental fabrication. Especially, the δ-doping of Mott insulators [8][9][10][11] not only has relevance in the designing context, but furthermore sheds light on the generic physics of the realistic doped-Mott state in a controlled way without the usual complications arising from disorder and other features of random impurity doping.…”

Oxide Heterostructures from a Realistic Many-Body Perspective

“…While STO is an ideal cubic perovskite at ambient temperature, LTO marks a distorted perovskite with orthorhombic crystal symmetry. (Lechermann et al 2013)). Left: total spectrum, right: closer to Fermi level.…”

A novel quantum field approach to photoexcited insulators

“…For an electron the charge e q e = − and for a hole h q e = + and V is the potential energy associated with the band width. A restrictive presumption is the wavelength much larger than the lattice constant at which the nonstationary electric field E = −A  is regarded as spatially homogeneous and the terms 2 …”

“…In these strongly correlated materials interactions between the charged particles play a major role in determining optical and transport properties: each single particle has a complex influence on its neighbors and interacts with both antiparticles (electrons-holes) as well as with crystalline phonons. The elaborated models based on the density functional theory (DFT) and the dynamical mean-field theory of strongly correlated fermion systems (DMFT) which now became the standard for fermionic correlation problems [1][2][3]. Nevertheless, the uncertainty in the choice of model parameters prevent the DFT+DMFT approaches from being flexible enough to capture entirely the quantum many-body problem of realistic complexity.…”