MAGNETIC-FIELD DEPENDENCE OF THE DENSITY-OF-STATES OF YBA2CU3O6.95 AS DETERMINED FROM THE SPECIFIC-HEAT

The magnetic field dependence of the electronic density of states at the Fermi level, N(EF,H), is determined in single-crystal YBa2Cu3O6.95 by specific heat measurements. The total specific heat is best described by including two predictions for the electronic specific heat of d-wave superconductivity: a T2 term in zero field and an increased linear term in a magnetic field applied perpendicular to the CuO2 planes. The additional linear term, which implies a finite N(EF,H), obeys N(EF,H)(HHc2)12 as predicted by Volovik for superconductivity with lines of nodes in the gap. © 1994 The American Physical Society.