Effect of electron correlations on the lifshitz transition at the LaAlO3/SrTiO3 interface

Abstract

In the two-dimensional electron liquid emerging at the interface between two band insulators LaAlO3 and SrTiO3, it has been pointed out that the system undergoes a Lifshitz transition as the interface is doped with carriers. The topology of the Fermi surface is changed due to occupation of two new orbitals at the Fermi level at a critical carrier density. Here, we investigate the effect of local electron correlations and Lifshitz transition on the Seebeck coefficient. Using dynamical mean-field theory, we calculate the Seebeck coefficient and find that the Seebeck coefficient shows a cusp at a critical density. In the presence of inter-orbital electron-electron interaction, the critical density reduces due to the transfer of spectral weight towards lower energy near the r point.