Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

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

TT 6.7: Vortrag

Montag, 5. September 2022, 16:45–17:00, H22

Heavy quasiparticles in Fermi surface and electronic instabilities in the heavy-fermion superconductor CeRh₂As₂ — •Evrard-Ouicem Eljaouhari and Gertrud Zwicknagl — Institut f. Mathemat. Physik, TU Braunschweig, Braunschweig, Germany

We present calculations of the heavy quasiparticles in the heavy-fermion compound CeRh₂As₂ which exhibts multi-phase superconductivity[1]. The narrow quasiparticle bands that are derived from the Ce-4f degrees of freedom are calculated by means of the Renormalized Band (RB) method. The RB scheme provides a framework for a realistic description of the coherent low-energy excitations in a Fermi liquid which combines material-specific ab-initio methods and phenomenological considerations in the spirit of the Landau theory of Fermi liquids. The central focus of the present study is the role played by the non-symmorphic lattice structure and the consequences of the Crystalline Electric Field (CEF) which removes the orbital degeneracy of the Ce 4f states. We conjecture that the quasi-quartet CEF ground state in combination with pronounced nesting features of the Fermi surface may give rise to a quadrupole density wave [2].

This work is supported by the ANR-DFG program Fermi-NESt.

[1] S. Khim et al., Science 373, 1012 (2021)

[2] D. Hafner et al., Phys. Rev. X 12, 011023 (2022)