Heavy quasiparticles in CeRh2As2: Renormalized bands, Fermi surfaces, and electronic instabilities

The heavy-fermion superconductor CeRh2As2 exhibits a rich phase diagram at low temperatures. The observation of multi-phase superconductivity has been of particular interest [1]. The present contribution deals with the low-temperature normal state out of which the superconducting phases are forming. The central focus are the narrow quasiparticle bands and the electronic instabilities of the Fermi liquid state. We present calculations of the heavy quasiparticles in the heavy-fermion compound CeRh2As2. 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].



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

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