Extremely Correlated Fermi Liquids

TL;DR

This paper develops a theory for an extremely correlated Fermi liquid (ECFL) at infinite interaction strength, revealing unique spectral features and an energy scale that influence photoemission spectra, with implications for strongly correlated electron systems.

Contribution

The paper introduces a novel ECFL theory with a dual hierarchy of equations, providing new insights into spectral functions and coherence in highly correlated Fermi liquids.

Findings

Spectral functions show a broad background and temperature-dependent skew.

An energy scale Δ(k,x) significantly affects photoemission spectra.

A duality links apparent loss of coherence to the sharpness of the underlying FL.

Abstract

We present the theory of an extremely correlated Fermi liquid (ECFL) with $U\to \infty$. This liquid has an underlying Fermi liquid (FL) Greens function that is further caparisoned. The theory leads to two parallel hierarchies of equations that permit iterative approximations in a certain parameter. Preliminary results for the spectral functions display a broad background and a distinct $T$ dependent left skew. An important energy scale $\Delta(\vec{k},x)$ emerges as the average inelasticity of the FL Greens function, and influences the photoemission spectra profoundly. A duality is identified wherein an apparent loss of coherence of the ECFL results from an excessively sharp FL.