Observation of d-wave scaling relations in the mixed-state specific heat of YBa2Cu3O7

TL;DR

This study measures the low-temperature specific heat of YBa2Cu3O7 and finds that its anisotropic component follows a d-wave vortex scaling relation, confirming theoretical predictions about line nodes in high-temperature superconductors.

Contribution

The paper provides experimental evidence that the anisotropic specific heat component in YBa2Cu3O7 obeys a d-wave vortex scaling relation, supporting theoretical models of line nodes.

Findings

Anisotropic specific heat component follows d-wave scaling relation.

Field and temperature dependence consistent with theoretical predictions.

Thermodynamic entropy variation aligns with measurements near Tc.

Abstract

The low temperature specific heat C(B,T) of an YBa2Cu3O7.00 single crystal is measured from 1.2 to 10 K in magnetic fields up to 14 T. The anisotropic component Caniso(T,B)=C(T,B//c)-C(T,B//ab) is a pure vortex quantity obtained directly from experiment. It follows a scaling relation predicted recently for line nodes characteristic of d-wave vortices. Our experimental field and temperature range corresponds to a crossover region where the limit Caniso(T,B)is proportional to T*sqrt(B) does not strictly apply. The variation of the entropy caused by the magnetic field at low T is thermodynamically compatible with measurements near Tc.