Electronic Specific Heat of La_{2-x}Sr_{x}CuO_{4}: Pseudogap Formation and Reduction of the Superconducting Condensation Energy

TL;DR

This study investigates the pseudogap phenomenon and its impact on superconducting condensation energy in La_{2-x}Sr_{x}CuO_{4} through specific heat measurements, revealing a reduced energy scale related to coherent pairing over the Fermi arc.

Contribution

It introduces an effective superconducting energy scale that accounts for pseudogap effects, providing new insight into the reduction of condensation energy in cuprates.

Findings

Pseudogap appears in specific heat data for doping p<0.2.

Superconducting condensation energy U(0) is significantly reduced in the pseudogap regime.

An effective energy scale ff = eta p  \u03b4_0 explains the reduction of U(0).

Abstract

To examine the so-called small pseudogap and the superconducting (SC) condensation energy U(0), the electronic specific heat Cel was measured on La_{2-x}Sr_{x}CuO_{4} up to ~120K. In samples with doping level p (=x) less than ~0.2, small pseudogap behavior appears in the \gamma (=Cel/T) vs. T curve around the mean-field critical temperature for a d-wave superconductor Tco (=2*\Delta_{0}/(4~5)k_B), where \Delta_{0} is the maximum gap at T<<Tc. The condensation energy U(0) is largely reduced in the pseudogap regime (p< ~0.2). The reduction of U(0) can be well reproduced by introducing an effective SC energy scale \Delta_{eff}=\beta*p*\Delta_{0} (\beta=4.5) instead of \Delta_{0}. The effective SC energy scale is discussed in relation to the coherent pairing gap formed over the nodal Fermi arc.