Pressure-induced change of the pairing symmetry in superconducting CeCu2Si2

TL;DR

This study investigates how hydrostatic pressure influences the pairing symmetry in CeCu2Si2, revealing two distinct superconducting regions with different underlying mechanisms, as evidenced by thermodynamic property variations.

Contribution

It provides experimental evidence of pressure-induced changes in pairing symmetry and identifies two separate superconducting regimes in CeCu2Si2.

Findings

Identification of two distinct superconducting regions under pressure

Different thermodynamic properties in low and high-pressure SC phases

Support for different pairing mechanisms in each SC region

Abstract

Low-temperature (T) heat-capacity measurements under hydrostatic pressure of up to p=2.1 GPa have been performed on single-crystalline CeCu2Si2. A broad superconducting (SC) region exists in the T-p phase diagram. In the low-pressure region antiferromagnetic spin fluctuations and in the high-pressure region valence fluctuations had previously been proposed to mediate Cooper pairing. We could identify these two distinct SC regions. We found different thermodynamic properties of the SC phase in both regions, supporting the proposal that different mechanisms might be implied in the formation of superconductivity.