AUTHOR=Onishi Seita , Stockert Ulrike , Khim Seunghyun , Banda Jacintha , Brando Manuel , Hassinger Elena 

TITLE=Low-Temperature Thermal Conductivity of the Two-Phase Superconductor CeRh2As2

JOURNAL=Frontiers in Electronic Materials

VOLUME=2

YEAR=2022

URL=https://www.frontiersin.org/journals/electronic-materials/articles/10.3389/femat.2022.880579

DOI=10.3389/femat.2022.880579

ISSN=2673-9895

ABSTRACT=<p>CeRh<sub>2</sub>As<sub>2</sub> is a rare unconventional superconductor (<italic>T</italic><sub>c</sub> = 0.26 K) characterized by two adjacent superconducting phases for a magnetic field <italic>H</italic>‖<italic>c</italic>-axis of the tetragonal crystal structure. Antiferromagnetic order, quadrupole-density-wave order (<italic>T</italic><sub>0</sub> = 0.4 K) and the proximity of this material to a quantum-critical point have also been reported: The coexistence of these phenomena with superconductivity is currently under discussion. Here, we present thermal conductivity and electrical resistivity measurements on a single crystal of CeRh<sub>2</sub>As<sub>2</sub> between 60 mK and 200 K and in magnetic fields (<italic>H</italic>‖<italic>c</italic>) up to 8 T. Extrapolation of our normal-state data to zero temperature validates the Wiedemann-Franz law within the error bars. The <italic>T</italic> dependence of the thermal conductivity <italic>κ</italic>(<italic>T</italic>) shows a pronounced drop below <italic>T</italic><sub>c</sub> which is also field dependent and thus interpreted as the signature of superconductivity. However, the large residual resistivity and the lack of sharp anomalies in <italic>κ</italic>(<italic>T</italic>) at the expected transition temperatures clearly indicate that samples of much higher purity are required to gain more information about the superconducting gap structure.</p>