Regensburg 2022 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 6: Kondo Physics, f-Electron Systems and Heavy Fermions

TT 6.8: Vortrag

Montag, 5. September 2022, 17:00–17:15, H22

Muon spin rotation/relaxation studies on the heavy-fermion superconductor CeRh₂As₂ — •Seunghyun Khim¹, Manuel Brando¹, Oliver Stockert¹, Christoph Geibel¹, Zurab Guguchia², Robert Scheuermann², Debarchan Das², and Toni Shiroka² — ¹Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany — ²Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, Villigen PSI, Switzerland

We study magnetic and superconducting (SC) properties of the unconventional superconductor CeRh₂As₂ (T_c ∼ 0.3 K) by means of muon spin rotation/relaxation (µSR) experiments. No clear evidence of oscillation is identified in zero-field µSR spectra down to 0.27 K while the relaxation rate moderately increases below ∼ 0.4 K. This could be associated with the suggested quadrupole-density-wave order at T₀ ≈ 0.4 K and the antiferromagnetic order at T_N ≈ 0.27 K. In weak transverse-field (TF) µSR measurements, a pronounced increase in the relaxation rate was observed in the SC state. The relaxation rate (σ_s), regarded as a direct measure of the magnetic penetration depth λ (σ_s ∝ 1 / λ²), almost flattens below T/T_c ∼ 0.2, being strongly indicative of suppressed quasiparticle excitations. TF-µSR measurements under 2 T reveal a power-law-like T-dependent relaxation rate in the normal state, indicating critical fluctuations. Furthermore, this relaxation rate increases with fields in both the normal and SC state, implying unusual magnetism. Our observations suggest CeRh₂As₂ to have a nearly fully-gapped SC behavior in the vicinity of a peculiar quantum critical point.