Non-Fermi liquid behavior at the onset of incommensurate 2k_F charge or spin density wave order in two dimensions

TL;DR

This paper investigates how quantum critical fluctuations near incommensurate 2k_F charge or spin density wave transitions in two-dimensional metals lead to non-Fermi liquid behavior, with distinct decay rates depending on hot spot configurations.

Contribution

It provides a perturbative analysis of fluctuation effects on single-particle excitations, revealing non-Fermi liquid power laws with specific exponents for different hot spot scenarios.

Findings

Single hot spot pair yields a 2/3 power law decay rate.

Two hot spot pairs produce a linear decay rate with particle-hole asymmetry.

Results highlight the non-Fermi liquid nature at quantum critical points.

Abstract

We analyze the influence of quantum critical fluctuations on single-particle excitations at the onset of incommensurate $2k_F$ charge or spin density wave order in two-dimensional metals. The case of a single pair of hot spots at high symmetry positions on the Fermi surface needs to be distinguished from the case of two hot spot pairs. We compute the fluctuation propagator and the electronic self-energy perturbatively in leading order. The energy dependence of the single-particle decay rate at the hot spots obeys non-Fermi liquid power laws, with an exponent 2/3 in the case of a single hot spot pair, and exponent one for two hot spot pairs. The prefactors of the linear behavior obtained in the latter case are not particle-hole symmetric.