Adaptation of the Landau-Migdal Quasiparticle Pattern to Strongly Correlated Fermi Systems

TL;DR

This paper extends Landau's Fermi liquid theory to strongly correlated Fermi systems with a quantum critical point, revealing topological phase transitions and flat-spectrum states that explain classical behavior near criticality.

Contribution

It adapts the Landau-Migdal quasiparticle pattern to describe topological transitions and flat-spectrum states in strongly correlated Fermi systems at a QCP.

Findings

Breakdown of Fermi liquid stability at QCP

Cascade of topological phase transitions

Emergence of flat-spectrum states at zero temperature

Abstract

A quasiparticle pattern advanced in Landau's first article on Fermi liquid theory is adapted to elucidate the properties of a class of strongly correlated Fermi systems characterized by a Lifshitz phase diagram featuring a quantum critical point (QCP) where the density of states diverges. The necessary condition for stability of the Landau Fermi Liquid state is shown to break down in such systems, triggering a cascade of topological phase transitions that lead, without symmetry violation, to states with multi-connected Fermi surfaces. The end point of this evolution is found to be an exceptional state whose spectrum of single-particle excitations exhibits a completely flat portion at zero temperature. Analysis of the evolution of the temperature dependence of the single-particle spectrum yields results that provide a natural explanation of classical behavior of this class of Fermi systems in the QCP region.