Frist Principles Study of the Fermi Surface Topology of CeCu₂Si₂

Since the discovery of heavy-fermion superconductivity in CeCu₂Si₂, the material has attracted interest in the nature of superconducting pairing. So, it is essential to better understand the electronic Fermi surface topology and its role in strong antiferromagnetic fluctuations. We have performed electronic ground state calculations on CeCu₂Si₂ using the Gutzwiller approximation. This method captures the quasiparticle band renormalization from the strong onsite Coulomb repulsion. We have performed an analysis of 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 quasiparticle mass renormalization in the energy bands. Our results confirm two Fermi surface sheets corresponding to the heavy and light quasiparticles, which is in agreement with the renormalized band method. We also discuss the connection of the Fermi surface topology to hot-spots in the magnetic susceptibility form factor measured by neutron scattering.