Nodeless Superconducting State in the Presence of Zero-Field Staggered Magnetization in CeRh$_{2}$As$_{2}$

J. Juraszek; G. Chajewski; D. Kaczorowski; M. Konczykowski; D. F. Agterberg; T. Cichorek

paper

Nodeless Superconducting State in the Presence of Zero-Field Staggered Magnetization in CeRh $_{2}$ As $_{2}$

arXiv:2502.14423

Abstract

The tetragonal heavy-fermion superconductor CeRh $_{2}$ As $_{2}$ with a critical temperature $T_{c}$ $\approx$ 0.34 K exhibits an intriguing magnetic field-induced transition between likely distinct superconducting states. In zero field, an even-parity state emerges within another ordered phase of unknown origin with $T_{0}$ $\approx$ 0.54 K. Here, we investigated the spin-singlet state of CeRh $_{2}$ As $_{2}$ at temperatures down to $\approx$ 0.02 $T_{c}$ by means of local magnetization measurements performed using micro-Hall probe magnetometry. We determined the temperature dependencies of the lower critical field for both in-plane and out-of-plane field directions, and demonstrated their consistency with predominantly fully gapped superconductivity. In the magnetization measured along the $a$ axis, we found a clear increase below $T_{0}$ , while no similar anomaly was observed along the $c$ axis. Our results place important constraints on the spin-singlet order parameter in CeRh $_{2}$ As $_{2}$ and highlight an important role of static magnetic moments in the nature of $T_{0}$ phase.

19 pages, 12 figures

Nodeless Superconducting State in the Presence of Zero-Field Staggered Magnetization in CeRh2​As2​

Abstract

Nodeless Superconducting State in the Presence of Zero-Field Staggered Magnetization in CeRh $_{2}$ As $_{2}$