Structural Phase Transitions of the Metal Oxide Perovskites SrTiO3, LaAlO3 and LaTiO3 Studied with a Screened Hybrid Functional

TL;DR

This study uses the HSE06 hybrid functional to accurately model structural phase transitions and electronic properties of key metal oxide perovskites, improving upon previous methods and aligning well with experimental data.

Contribution

It demonstrates that HSE06 provides significantly improved predictions of structural and electronic properties of perovskite oxides compared to semilocal functionals.

Findings

HSE06 yields better lattice parameters and electronic properties.

Predicted crystal field splittings match experimental values.

Identified LaTiO₃ as a Mott insulator and revealed orbital order indications.

Abstract

We have investigated the structural phase transitions of the transition metal oxide perovskites SrTiO$_{3}$, LaAlO$_{3}$ and LaTiO$_{3}$ using the screened hybrid density functional of Heyd, Scuseria and Ernzerhof (HSE06). We show that HSE06-computed lattice parameters, octahedral tilts and rotations, as well as electronic properties, are significantly improved over semilocal functionals. We predict the crystal field splitting ($\Delta_{CF}$) resulting from the structural phase transition in SrTiO$_{3}$ and LaAlO$_{3}$ to be 3 meV and 10 meV, respectively, in excellent agreement with experimental results. HSE06 identifies correctly LaTiO$_{3}$ in the magnetic sates as a Mott insulator. Also, it predicts that the GdFeO$_{3}$-type distortion in non-magnetic LaTiO$_{3}$ will induce a large $\Delta_{CF}$ of 410 meV. This large crystal-field splitting associated with the large magnetic moment found in the G-type antiferromagnetic state suggest that LaTiO$_{3}$ has an induced orbital order, which is confirmed by the visualisation of the highest occupied orbitals. These results strongly indicate that HSE06 is capable of efficiently and accurately modeling perovskite oxides, and promises to efficiently capture the physics at their heterointerfaces.