Ab Initio Charge Transport in the Polaron Regime in Transition Metal Oxides

Strong electron-phonon (e-ph) interactions lead to the formation of polarons, quasiparticles consisting of an electron carrying a phonon cloud. Polaron formation lowers the mobility and greatly affects charge transport in transition metal oxides and other polar compounds. Here, we develop a many-body ab initio approach to compute charge transport including polaron effects. We apply our approach to the two perovskite oxides BaSnO₃ and SrTiO₃, and analyze in detail how and why polaron formation affects charge transport in these materials. The calculations are connected with our recent work on SrTiO₃, where, using the Boltzmann Transport equation with lowest-order e-ph scattering, we accurately predicted the temperature dependence of the mobility in SrTiO₃ [1], whose absolute value was however higher than experiment. We show how including polaron effects can correct the lowest-order result, improving agreement with experiment.

[1] J.-J. Zhou, O. Hellman, and M. Bernardi, arXiv:1806.05775 (2018).