Electronic and dynamical properties of CeRh$_{2}$As$_{2}$: Role of Rh$_{2}$As$_{2}$ layers and expected hidden orbital order

TL;DR

This paper investigates the electronic and dynamical properties of CeRh$_{2}$As$_{2}$, highlighting the influence of Rh$_{2}$As$_{2}$ layers, hidden orbital order, and potential Lifshitz transition under magnetic field, relevant for its unusual superconducting phases.

Contribution

It reveals the impact of Rh$_{2}$As$_{2}$ layers and hidden orbital order on CeRh$_{2}$As$_{2}$'s electronic structure, and suggests a Lifshitz transition induced by magnetic field.

Findings

Electronic band structure mainly involves Ce 4f and Rh 4d orbitals.

Presence of hidden orbital order due to Ce atom positioning.

Potential Lifshitz transition under external magnetic field.

Abstract

Recently discovered heavy fermion CeRh$_{2}$As$_{2}$ compound crystallizes in the nonsymmorphic $P4/nmm$ symmetry, which enables the occurrence of topological protection. Experimental results show that this material exhibits unusual behavior, which is manifested by the appearance of two superconducting phases. In this work, we uncover and discuss a role of Rh$_{2}$As$_{2}$ layers and their impact on the electronic and dynamical properties of the system. The location of Ce atoms between two non-equivalent layers allows for the realization of hidden orbital order. We point out that the electronic band structure around the Fermi level is associated mostly with Ce $4f$ and Rh $4d$ orbitals and suggest the occurrence of the Lifshitz transition induced by the external magnetic field. We discuss also the role played by the $f$--$d$ orbital hybridization in the electronic band structure.