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TT: Fachverband Tiefe Temperaturen

TT 52: Heavy Fermions

TT 52.1: Vortrag

Mittwoch, 11. März 2026, 15:00–15:15, HSZ/0103

High-field muon spin resonance/rotation (µSR) studies on CeRh₂As₂ — •Seunghyun Khim¹, Oliver Stockert¹, Andrin Doll², and Robert Scheuermann² — ¹Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — ²Paul Scherrer Institute, Villigen, Switzerland

The heavy-fermion CeRh₂As₂ with T_c = 0.35 K exhibits unique two-phase superconductivity under a c-axis magnetic field. In the superconducting (SC) state, a field-induced transition at H^* = 4 T separates a low-field even-parity (SC1) phase from a high-field odd-parity (SC2) phase. In addition, an unusual ordering of the Ce-4f moments emerges below T₀ = 0.55 K, which is suppressed with increasing c-axis field. The T₀ phase boundary smoothly extends into the SC2 phase and persists to zero temperature at approximately 7 T. Previous zero-field µSR studies have identified that an internal field develops spontaneously below T₀ and becomes nearly saturated below T_c, suggesting a possible correlation between the magnetic order and superconductivity. Here, we present following high-field µSR measurements up to 7.5 T. Temperature-dependent measurements at 2 T show that the internal field is fully established below 0.3 K, coinciding with the onset of the SC1 phase. Furthermore, field-dependent measurements at 20 mK reveal that the internal field begins to be suppressed above 4 T and then vanishes entirely at around 7 T. These observations propose that the magnetic order in the T₀ phase is locked in exclusively within the SC1 phase, reflecting an intricate coupling between the magnetic and SC order parameters.

Keywords: muon spin rotation; magnetism; superconductivity