Unusual behaviours and Impurity Effects in the Noncentrosymmetric Superconductor CePt3Si

TL;DR

This study investigates how impurities, defects, and growth conditions affect the superconducting properties of noncentrosymmetric CePt3Si, revealing robustness of line nodes and intrinsic broad transition features, with some discrepancies in transition temperature measurements.

Contribution

It provides new insights into impurity effects and intrinsic properties of CePt3Si, highlighting differences from centrosymmetric unconventional superconductors.

Findings

Linear low-temperature penetration depth is robust against impurities.

Superconducting transition temperature is consistently around 0.75 K.

Discrepancies exist between different measurement techniques of Tc.

Abstract

We report a study in which the effect of defects/impurities, growth process, off-stoichiometry, and presence of impurity phases on the superconducting properties of noncentrosymmetric CePt3Si is analysed by means of the temperature dependence of the magnetic penetration depth. We found that the linear low-temperature response of the penetration depth -indicative of line nodes in this material- is robust regarding sample quality, in contrast to what is observed in unconventional centrosymmetric superconductors with line nodes. We discuss evidence that the broadness of the superconducting transition may be intrinsic, though not implying the existence of a second superconducting transition. The superconducting transition temperature systematically occurs around 0.75 K in our measurements, in agreement with resistivity and ac magnetic susceptibility data but in conflict with specific heat, thermal conductivity and NMR data in which Tc is about 0.5 K. Random defects do not change the linear low-temperature dependence of the penetration depth in the heavy-fermion CePt3Si with line nodes, as they do in unconventional centrosymmetric superconductors with line nodes.