2025/02/20 by J. Juraszek, Juraszek, J., Grzegorz Chajewski +9
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #Superconductivity (cond-mat.supr-con)
paper · pdf · doi:10.48550/arxiv.2502.14423
openalex publication_date 2025/02/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The tetragonal heavy-fermion superconductor CeRh2As2 with a critical temperature Tc ≈ 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 T0 ≈ 0.54 K. Here, we investigated the spin-singlet state of CeRh2As2 at temperatures down to ≈ 0.02Tc 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 T0, while no similar anomaly was observed along the c axis. Our results place important constraints on the spin-singlet order parameter in CeRh2As2 and highlight an important role of static magnetic moments in the nature of T0 phase.