Lattice effects on nematic quantum criticality in metals

TL;DR

This paper demonstrates that lattice coupling significantly alters the behavior of nematic quantum criticality in metals, often preserving Fermi liquid properties instead of non-Fermi liquid behavior predicted by electron-only theories.

Contribution

It introduces the impact of lattice coupling on nematic quantum criticality, showing that lattice shear modes cut off critical fluctuations, leading to Fermi liquid behavior at low temperatures.

Findings

Lattice coupling suppresses non-Fermi liquid behavior near the quantum critical point.

Depending on Fermi surface geometry, hot spots may be limited or absent.

Predictions are relevant for iron-based superconductors.

Abstract

Theoretically, it is commonly held that in metals near a nematic quantum critical point the electronic excitations become incoherent on the entire `hot' Fermi surface, triggering non Fermi liquid behavior. However, such conclusions are based on electron-only theories, ignoring a symmetry-allowed coupling between the electronic nematic variable and a suitable crystalline lattice strain. Here we show that including this coupling leads to entirely different conclusions because the critical fluctuations are mostly cutoff by the non-critical lattice shear modes. At sufficiently low temperatures the thermodynamics remain Fermi liquid type, while, depending on the Fermi surface geometry, either the entire Fermi surface stays cold, or at most there are hot spots. In particular, our predictions are relevant for the iron-based superconductors.