Magnetic order and electronic structure of [110]-oriented LaTiO₃ films: A theoretical study

School of Science, Nanjing University of Posts and Telecommunications - Nanjing 210023, China

^(a) wyk@njupt.edu.cn (corresponding author)
^(b) lixa@njupt.edu.cn

Received: 1 September 2021
Accepted: 3 November 2021

Abstract

The epitaxial strain effects on the magnetic ground state and electronic structure of [110]-oriented LaTiO₃ films have been calculated using the density functional theory. First, the lattice constants of the a-axis and c-axis are fixed to study. For the compressive strain, a magnetic phase transition from the original G-type antiferromagnet to A-type antiferromagnet is predicted when using the SrTiO₃, LaGaO₃, and LaAlO₃ substrates, similar to the [001] case. Interestingly, a new magnetic phase, i.e., the ferromagnetic order, will appear when the larger compressive LaSrAlO₄ is used. For the tensile strain, although the G-type antiferromagnetic order is robust as the ground state, the exchange couplings are significantly increased, which will enhance the Néel temperature. Furthermore, the contributions of d_yz, d_xz and d_xy orbitals to the bands near the Fermi level show an obvious difference due to the Jahn-Teller distortions. For comparison, the case with fixed b-axis and c-axis is also tested, which shows that the compressive strained LaTiO₃ remains the G-type antiferromagnetic order while the tensile strained LaTiO₃ exhibits the A-type antiferromagnetic order. The underlying physical mechanisms are the lattice distortions, including the Ti-O-Ti bond angles and Ti-O bond lengths.