Electronic properties of LaAlO₃/SrTiO₃n-type interfaces: a GGA+Ustudy

Abstract

The role of electronic correlation effects for a realistic description of the electronic properties of [Formula: see text]/[Formula: see text] heterostructures as covered by the on-site Coulomb repulsion within the GGA+U approach is investigated. Performing a systematic variation of the values of the Coulomb parameters applied to the Ti 3d and La 4f orbitals we put previous suggestions to include a large value for the La 4f states into perspective. Furthermore, our calculations provide deeper insight into the band gap landscape in the space spanned by these Coulomb parameters and the resulting complex interference effects. In addition, we identify important correlations between the local Coulomb interaction within the La 4f shell, the band gap, and the atomic displacements at the interface. In particular, these on-site Coulomb interactions influence buckling within the LaO interface layer, which via its strong coupling to the electrostatic potential in the LAO overlayer causes considerable shifts of the electronic states at the surface and eventually controls the band gap.

Electronic properties and surface reactivity of SrO-terminated SrTiO3 and SrO-terminated iron-doped SrTiO3

“…That is why in this study we have employed the GGA+U approach for the d-orbitals of Ti and Fe. The value of U for Ti was estimated to be 8.0 eV by reproducing the optical band of SrTiO 3 , 3.2 eV, and comparing with data from the literature [ 26 ]. The value of U for Fe, 3.0 eV, is taken from the literature where it was optimized for SrFeO 3 [ 27 ].…”

Magnetic Properties of LaAlO3/SrTiO3 Heterostructure Modelled on a Supercomputer

“…The ab initio calculations were based on DFT [4] in the framework of the GGA+U method, with additional local correlations of U = 2 eV to the Ti 3d orbitals and U = 8 eV to the La 4f orbitals [5]. We used Vienna Ab-Initio Simulation Package (VASP) [6], which is part of the MedeA R software of Materials Design.…”

“…To study the heterostructure with defects, we used 2 × 2 in-plane supercells of the bare heterostructures [7] with introduced oxygen vacancies and hydrogen dopants at the surface, or in an interfacial layer on both sides while preserving the inversion symmetry of the slabs. More details about computation parameters and slab geometry can be found in [5,7,8].…”

Ab initio investigation of electronic and magnetic properties of antiferromagnetic/ferroelectric LaMnO3/BaTiO3 interface

“…Therefore, the U−J parameters were added to La 4f, Ti 3d and Mn 4d (U=8 eV, 2 eV and 4 eV, respectively). This choice was based on our previous detailed investigation of the effect of local electronic correlations as captured by the GGA+U method [39], as well as [40]. In ourprevious study of U effect on the LaAlO 3 /SrTiO 3 system we have concluded that U parameter is important and it affects quantitatively the band gap.…”