Low energy excitations and singular contributions in the thermodynamics of clean Fermi liquids

TL;DR

This paper uses a bosonization method to analyze low energy excitations in 2D Fermi liquids, revealing anomalous thermodynamic contributions and potential triplet pairing instabilities.

Contribution

It introduces a modified bosonization approach that isolates low energy effects and calculates specific heat corrections, highlighting singlet and triplet excitation contributions.

Findings

Logarithmic temperature corrections to specific heat are derived.

Singlet and triplet excitation contributions are identified.

Triplet excitations may diverge, indicating possible triplet pairing.

Abstract

Using a recently suggested method of bosonization in an arbitrary dimension, we study the anomalous contribution of the low energy spin and charge excitations to thermodynamic quantities of a two-dimensional (2D) Fermi liquid. The method is slightly modified for the present purpose such that the effective supersymmetric action no longer contains the high energy degrees of freedom but still accounts for effects of the finite curvature of the Fermi surface. Calculating the anomalous contribution $\delta c(T)$ to the specific heat, we show that the leading logarithmic in temperature corrections to $\delta c(T)/T^2$ can be obtained in a scheme combining a summation of ladder diagrams and renormalization group equations. The final result is represented as the sum of two separate terms that can be interpreted as coming from singlet and triplet superconducting excitations. The latter may diverge in certain regions of the coupling constants, which should correspond to the formation of triplet Cooper pairs.