Field-angle Dependence of the Zero-Energy Density of States in the Unconventional Heavy-Fermion Superconductor CeCoIn5

TL;DR

This study investigates how the specific heat of CeCoIn5 varies with magnetic field angle, revealing fourfold oscillations that confirm the presence of gap nodes and suggest a dxy gap symmetry in this heavy-fermion superconductor.

Contribution

The paper provides direct experimental evidence of gap nodes and identifies the likely dxy symmetry of the superconducting gap in CeCoIn5 through field-angle dependent specific heat measurements.

Findings

Fourfold angular oscillation in specific heat observed.

Gap nodes confirmed by oscillation persistence at low fields.

Superconducting gap symmetry likely dxy type.

Abstract

Field-angle dependent specific heat measurement has been done on the heavy-fermion superconductor CeCoIn5 down to ~ 0.29 K, in a magnetic field rotating in the tetragonal c-plane. A clear fourfold angular oscillation is observed in the specific heat with the minima (maxima) occurring along the [100] ([110]) directions. Oscillation persists down to low fields H << Hc2, thus directly proving the existence of gap nodes. The results indicate that the superconducting gap symmetry is most probably of dxy type.