Line nodes in the superconducting gap function of noncentrosymmetric CePt_3Si

TL;DR

This study investigates the superconducting gap structure of CePt_3Si, revealing evidence of line nodes through thermal transport measurements, which constrains the possible symmetry of its order parameter.

Contribution

It provides experimental evidence for line nodes in the superconducting gap of CePt_3Si, a noncentrosymmetric heavy fermion superconductor, using thermal conductivity measurements.

Findings

Residual T-linear term consistent with nodal gap structure

Rapid increase in thermal conductivity with magnetic field

Scaling behavior of thermal conductivity with T/√H

Abstract

The superconducting gap structure of recently discovered heavy fermion CePt_3Si without spatial inversion symmetry was investigated by thermal transport measurements down to 40 mK. In zero field a residual T-linear term was clearly resolved as T-> 0, with a magnitude in good agreement with the value expected for a residual normal fluid with a nodal gap structure, together with a T^2-dependence at high temperatures. With an applied magnetic fields, the thermal conductivity grows rapidly, in dramatic contrast to fully gapped superconductors, and exhibits one-parameter scaling with T/sqrt{H}. These results place an important constraint on the order parameter symmetry, that is CePt_3Si is most likely to have line nodes.