Superconducting gap on the Fermi arcs and condensation energy in La2-xSrxCuO4La2-xSrxCuO4 single crystals

The low temperature specific heat of La2-xSrxCuO4La2-xSrxCuO4 single crystals (0.063⩽x⩽0.238)(0.063⩽x⩽0.238) has been measured. From the field induced quasiparticle density of states, we derived the superconducting gap slope near the nodes. Based on the picture of superconducting gapping on the Fermi arcs and the formalism of Bardeen–Copper–Schrieffer theory, we obtained the doping dependence of the superconducting condensation energy and found that it is close to that determined by calculating directly from the entropy difference between the superconducting state and the normal state. Our analysis suggests that the coherent superconducting state is formed by forming a new gap on the Fermi arcs (or pockets) below TcTc.