Quantum criticality of d-wave quasiparticles and superconducting phase fluctuations

TL;DR

This paper extends the QED3 theory to finite temperatures in underdoped cuprates, revealing how vortex fluctuations influence quasiparticle behavior and thermodynamics, showing non-Fermi liquid characteristics.

Contribution

It introduces a finite temperature extension of the QED3 theory, elucidating the impact of vortex fluctuations on quasiparticle interactions and thermodynamic properties in cuprates.

Findings

Spin susceptibility scales as T^2 at low T and transitions to ~T at higher T.

Electronic specific heat scales as T^2 at low T.

Wilson ratio approaches zero as T approaches zero.

Abstract

We present finite temperature extension of the QED$_3$ theory of underdoped cuprates. The theory describes nodal quasiparticles whose interactions with quantum proliferated vortex-antivortex pairs are represented by an emergent U(1) gauge field. Finite temperature introduces a scale beyond which the long wavelength fluctuations in the spatial components of vorticity are suppressed. As a result, the spin susceptibility of the pseudogap state is bounded by $T^2$ at low T and crosses over to $\sim T$ at higher $T$, while the low-$T$ electronic specific heat scales as $T^2$, reflecting the thermodynamics of QED$_3$. The Wilson ratio vanishes as $T\to 0$. This non-Fermi liquid behavior originates from two general principles: spin correlations induced by ``gauge'' interactions of quasiparticles and fluctuating vortices and the ``relativistic'' scaling of the T=0 fixed point.