TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.17.4.116
TI  - Single-gap isotropic $s-$wave superconductivity in single crystals AuSn$_4$
PY  - 2024/10/21
UR  - https://scipost.org/SciPostPhys.17.4.116
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 17
IS  - 4
SP  - 116
A1  - Ghimire, Sunil
AU  - Joshi, Kamal R.
AU  - Krenkel, Elizabeth H.
AU  - Tanatar, Makariy
AU  - Konczykowski, Marcin
AU  - Grasset, Romain
AU  - Canfield, Paul
AU  - Prozorov, Ruslan
AB  - London, $\lambda_L (T)$, and Campbell, $\lambda_{C} (T)$, penetration depths were measured in single crystals of a topological superconductor candidate AuSn$_4$. At low temperatures, $\lambda_L (T)$ is exponentially attenuated and, if fitted with the power law, $\lambda(T) \sim T^n$, gives exponents $n>4$, indistinguishable from the isotropic single $s-$wave gap Bardeen-Cooper-Schrieffer (BCS) asymptotic. The superfluid density fits perfectly in the entire temperature range to the BCS theory. The superconducting transition temperature, $T_c = 2.40 ± 0.05$ K, does not change after 2.5 MeV electron irradiation, indicating the validity of the Anderson theorem for isotropic $s-$wave superconductors. Campbell penetration depth before and after electron irradiation shows no hysteresis between the zero-field cooling (ZFC) and field cooling (FC) protocols, consistent with the parabolic pinning potential. Interestingly, the critical current density estimated from the original Campbell theory decreases after irradiation, implying that a more sophisticated theory involving collective effects is needed to describe vortex pinning in this system. In general, our thermodynamic measurements strongly suggest that the bulk response of the AuSn$_4$ crystals is fully consistent with the isotropic $s-$wave weak-coupling BCS superconductivity.
ER  -

@Article{10.21468/SciPostPhys.17.4.116,
	title={{Single-gap isotropic $s-$wave superconductivity in single crystals AuSn$_4$}},
	author={Sunil Ghimire and Kamal R. Joshi and Elizabeth H. Krenkel and Makariy A. Tanatar and Marcin Kończykowski and Romain Grasset and Paul C. Canfield and Ruslan Prozorov},
	journal={SciPost Phys.},
	volume={17},
	pages={116},
	year={2024},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.17.4.116},
	url={https://scipost.org/10.21468/SciPostPhys.17.4.116},
}