Quantum criticality of d-wave quasiparticles and superconducting phase fluctuations -: art. no. 237001

We present finite temperature (T) extension of the (2+1)-dimensional QED (QED(3)) theory of underdoped cuprates. The theory describes nodal quasiparticles whose interactions with quantum proliferated hc/2e vortex-antivortex pairs are represented by an emergent U(1) gauge field. Finite T introduces a scale beyond which the spatial fluctuations 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 similar toT at higher T, while the low-T specific heat scales as T-2, reflecting the thermodynamics of QED(3). The Wilson ratio vanishes as T-->0; the pseudogap state is a thermal (semi)metal but a spin-charge dielectric. 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.