Self-energy enhancements in doped Mott insulators

TL;DR

This paper investigates how the self-energy of electrons in doped Mott insulators is enhanced away from the Fermi surface, revealing that chemical potential shifts can cause significant self-energy changes independent of electronic correlations.

Contribution

It demonstrates that chemical potential shifts, rather than hybridization or correlations, can cause self-energy enhancements in doped Mott insulators.

Findings

Self-energy at (pi,pi) is enhanced with hole doping for large U.

Self-energy at (0,0) is enhanced with electron doping.

Chemical potential shifts can induce large self-energy changes without altering electronic structure.

Abstract

We analyze enhancements in the magnitude of the self-energy for electrons far away from the Fermi surface in doped Mott insulators using the dynamical cluster approximation to the Hubbard model. For large onsite repulsion, U, and hole doping, the magnitude of the self-energy for imaginary frequencies at the top of the band (k=(pi,pi) is enhanced with respect to the self-energy magnitude at the bottom of the band (k=(0,0)). The self-energy behavior at these two k-points is switched for electron doping. Although the hybridization is much larger for (0,0) than for (pi,pi), we demonstrate that this is not the origin of this difference. Isolated clusters under a downward shift of the chemical potential, mu<U/2, at half-filling reproduce the overall self-energy behavior at (0,0) and (pi,pi) found in low hole doped embedded clusters. This happens although there is no change in the electronic structure of the isolated clusters. Our analysis shows that a downward shift of the chemical potential which weakly hole dopes the Mott insulator can lead to a large enhancement of the (pi,pi) self-energy which is not necessarily associated with electronic correlation effects, even in embedded clusters.