First-principles study of polar LaAlO (001) surface stabilization by point defects

Abstract

We use density functional theory to investigate the influence of surface vacancies on the surface stability of a stoichiometric free-standing LaAlO 3 (001) thin film. Defect-free three and five unit cell thick LaAlO 3 (001) thin films show macroscopic electric fields of 0.28 V/Å and 0.22 V/Å, respectively. The built-in electric field is sufficiently strong for the five unit cell thick film to undergo a dielectric breakdown in the local density approximation. We show that the electric field can be effectively compensated by La vacancies on the LaO surface, O vacancies on the AlO 2 surface, or both types of vacancy present at the same time. Comparing surface Gibbs free energies we show that several surface vacancy structures are thermodynamically stable.

Structural phase transitions of the metal oxide perovskites SrTiO3, LaAlO3, and LaTiO3studied with a scree

“…The SZVP basis set produces tilt angles 30% lower than those observed by plane wave calculations 72 which is very similar to the behavior we observed in the case of STO; we attribute this to the use of localized basis sets.…”

“…17 In the low-temperature rhombohedral phase, the LSDA and PBE lattice parameters tend to be higher than previous plane wave calculations. [70][71][72] The octahedral tilt angle for both LSDA and PBE is about 4…”

Electronic structure of (LaNiO3)2/(LaAlO3)Rüegg1, Mitra2, Demkov3 et al. 2012Phys. Rev. BSelf Cite7731440View full textAdd to dashboardCite

“…7,8,10 In this article, we discuss the electronic structure of a (111) bilayer of LaNiO 3 sandwiched between sufficiently large regions of LaAlO 3 . LaAlO 3 is a wide band-gap insulator 13 with an experimentally determined gap of E g = 5.6 eV while LaNiO 3 is a paramagnetic metal in bulk. The formal valence of nickel is Ni 3+ which corresponds to a partially filled 3d-shell with an electronic configuration t 6 2g e 1 g , i.e.…”

Designing defect spins for wafer-scale quantum technologies

“…A set of boundary conditions can be considered for the chemical potentials of the elements to provide a stability region for a host material within which the theoretical defect formation energies can be compared to each other. 63 One should also keep in mind that there might be other practical limitations in experimental samples. For instance, judicious engineering of the Fermi-level position by doping might be required to obtain a defect in a specifi c charge and spin state.…”

“…The stabilities of different defects in various charge and spin states can be determined by calculating the defect formation energies, 74 which are thermodynamic free energies as functions of the chemical potentials of the electron and the constituent elements. 63 The theoretical chemical potentials could be estimated for given experimental conditions, which is, however, nontrivial. Instead, the chemical potentials are usually treated as theoretical parameters in DFT calculations.…”