Intrinsic arrested nanoscale phase separation near a topological Lifshitz transition in strongly correlated two-band metals

TL;DR

This paper investigates how nanoscale phase separation occurs near a Lifshitz transition in a two-band Hubbard model, revealing critical points and conditions for inhomogeneous charge distribution relevant to cuprate superconductors.

Contribution

It identifies the phase separation diagram, quantum critical points, and the role of Coulomb interactions near a Lifshitz transition in strongly correlated two-band metals.

Findings

Nanoscale phase separation occurs near the Lifshitz transition.

A phase diagram as a function of charge density and energy shift is established.

Critical points with scale invariance are identified, relevant to cuprates.

Abstract

The arrested nanoscale phase separation in a two-band Hubbard model for strongly correlated charge carriers is shown to occur in a particular range in vicinity of the topological Lifshitz transition, where the Fermi energy crosses the bottom of the narrow band and a new sheet of the Fermi surface related to the charge carriers of the second band comes into play. We determine the phase separation diagram of this two-band Hubbard model as a function of two variables, the charge carrier density and the energy shift between the chemical potential and the bottom of the second band. In this phase diagram, we first determine a line of quantum critical points for the Lifshitz transition and find criteria for the electronic phase separation resulting in an inhomogeneous charge distribution. Finally, we identify the critical point in presence of a variable long-range Coulomb interaction where the scale invariance of the coexisting phases with different charge densities appears. We argue that this point is relevant for the regime of scale invariance of the nanoscale phase separation in cuprates like it was first observed in La$_2$CuO$_{4.1}$.