Two-component electron fluid in underdoped high-T_c cuprate superconductors

J. G. Storey¹ and J. L. Tallon^2a

¹ MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington - P.O. Box 500, Wellington, New Zealand
² MacDiarmid Institute, Industrial Research Ltd. - P.O. Box 31310, Lower Hutt, New Zealand

^a J.Tallon@irl.cri.nz

Received: 28 November 2011
Accepted: 8 March 2012

Abstract

Evidence from NMR of a two-component spin system in cuprate high-T_c superconductors is shown to be paralleled by similar evidence from the electronic entropy so that a two-component quasiparticle fluid is implicated. We propose that this two-component scenario is restricted to the optimal and underdoped regimes and arises from the upper and lower branches of the reconstructed energy-momentum dispersion proposed by Yang, Rice and Zhang (YRZ) to describe the pseudogap. We calculate the spin susceptibility within the YRZ formalism and show that the doping and temperature dependence reproduces the experimental data for the cuprates.