Electric Field Control of Jahn-Teller Distortions in Bulk Perovskites

The Jahn-Teller distortion, by its very nature, is often at the heart of the various electronic properties displayed by perovskites and related materials. Despite the Jahn-Teller mode being nonpolar, we devise and demonstrate, in the present Letter, an electric field control of Jahn-Teller distortions in bulk perovskites. The electric field control is enabled through an anharmonic lattice mode coupling between the Jahn-Teller distortion and a polar mode. We confirm this coupling and quantify it through first-principles calculations. The coupling will always exist within the $Pb{2}_{1}m$ space group, which is found to be the favored ground state for various perovskites under sufficient tensile epitaxial strain. Intriguingly, the calculations reveal that this mechanism is not only restricted to Jahn-Teller active systems, promising a general route to tune or induce novel electronic functionality in perovskites as a whole.

Figure 1

Schematic view of the main four lattice distortions involved in the $Pb{2}_{1}m$ phase of perovskites under tensile epitaxial strain. (a) Polar distortion (irreps ${\mathrm{\Gamma }}_5^{-}$), (b) $Q_2^{+}$ Jahn-Teller distortion (irreps $M_3^{+}$), (c) antipolar $A$ distortion (irreps $M_5^{+}$), (d) $a^0{a}^0{c}^{+}$ ${\varphi }_z^{+}$ antiferrodistortive motion (irreps $M_2^{+}$).

Figure 2

Potentials with respect to the amplitude of distortions of the four lattice motions producing the required $Pb{2}_{1}m$ for ${\mathrm{SrTiO}}_3$ (black filled circles), ${\mathrm{BaMnO}}_3$ (red filled squares), ${\mathrm{YMnO}}_3$ (blue filled diamonds), and ${\mathrm{BiFeO}}_3$ (green filled triangles) starting from the ideal $P4/mmm$ phase.

Figure 3

Projected density of states on the $d$ levels on two neighboring $B$ sites in the $(ab)$ plane of ${\mathrm{SrTiO}}_3$, ${\mathrm{BaMnO}}_3$, ${\mathrm{BiFeO}}_3$, and ${\mathrm{YMnO}}_3$. Local axes of the orbitals are displayed in Fig. 1. The Fermi level is located at 0 eV.

Figure 4

Electric field effect on the amplitude of the Jahn-Teller distortion (top panel) and the electronic gap value (bottom panel) on the four different compounds.