First-Principles Study of the Fermi Surface Topology of CeCu$_{2}$Si$_{2}$

TL;DR

This study uses advanced theoretical methods to analyze the Fermi surface topology of CeCu$_{2}$Si$_{2}$, revealing heavy and light quasiparticle sheets consistent with experimental data, enhancing understanding of its electronic structure.

Contribution

It applies the Gutzwiller wavefunction approximation to model strong correlations in CeCu$_{2}$Si$_{2}$, providing detailed insights into its Fermi surface topology beyond standard density functional theory.

Findings

Identifies two Fermi surface sheets with distinct quasiparticle masses.

Shows strong onsite Coulomb repulsion affects Fermi surface topology.

Results agree with experimental de Haas van Alphen measurements.

Abstract

Since the discovery of heavy-fermion superconductivity in CeCu$_{2}$Si$_{2}$, the material has attracted great interest particularly with regard to the nature of the superconducting pairing and its mechanism. Consequently, it is essential to better understand the electronic Fermi surface topology and its role in strong antiferromagnetic fluctuations. The standard density functional theory method is insufficient to model the interplay of strong onsite Coulomb repulsion in localized 4{\it f}-electrons and their hybridization with itinerant ligand-orbital electrons. We have performed electronic ground state calculations on CeCu$_{2}$Si$_{2}$ using the Gutzwiller wavefunction approximation. The Gutzwiller approximation captures the quasiparticle band renormalization from the strong onsite Coulomb repulsion. We have performed an analysis of this effect on the electronic structure and the Fermi surface topology by varying the interaction strength and taking into account the crystal-field splitting. Using the de Haas van Alphen effect, the extremal Fermi surface cross-sectional areas were calculated to quantify the effects of quasiparticle mass renormalization on the Fermi surface. Our results confirm two Fermi surface sheets corresponding to the heavy (488m$_{e}$) and light (4.35m$_{e}$) quasiparticles, which is in close agreement with experimental measurements as well as the renormalized band method.