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TT: Fachverband Tiefe Temperaturen

TT 11: Heavy Fermions

TT 11.5: Talk

Monday, March 18, 2024, 16:00–16:15, H 3005

Characteristic energy scales in CeRh₂As₂ — •O. Stockert¹, M. M. Koza², and S. Khim¹ — ¹Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany — ²Institut Laue-Langevin, Grenoble, France

The heavy-fermion superconductor CeRh₂As₂ is located close to a quantum critical point and attracts a lot of attention due to its interplay of unconventional heavy-fermion superconductivity with T_c ≈ 0.25 K and a possibly quadrupolar ordered state setting in above T_c. Recent measurements suggest the existence of antiferromagnetic order above the superconducting transition temperature. To better understand the unusual low-temperature properties of CeRh₂As₂, a knowledge of the relevant characteristic energy scales is important. We performed inelastic neutron scattering on CeRh₂As₂ powder to study the crystalline-electric-field (CEF) excitations and to look for the Kondo fluctuations. Our experiments reveal a low-lying excited CEF above the ground state doublet in addition to a Kondo enery scale of around 30 K. We will discuss our results in comparison to the previously suggested quadrupolar ground state and their implications for the ordered state.

Keywords: heavy-fermion superconductor; crystalline-electric-field excitations; Kondo effect; quadrupolar order