Lifshitz transition and metamagnetism: Thermoelectric studies of CeRu2 Si2

We report field- and temperature-dependent measurements of the thermoelectric power (TEP) across the pseudometamagnetic transition (MMT) in CeRu2Si2. We applied the thermoelectric gradient parallel and perpendicular to the field along the c axis of the tetragonal crystal which is the easy magnetization axis. At the MMT at Hm=7.8 T, a strong anomaly in the TEP is observed for both configurations with opposite signs. The anomaly at Hm becomes a cascade of anomalies at very low temperature which seems to be a generic feature of the TEP at a change in the topology of the Fermi surface (FS) in heavy Fermion multiband systems. Simultaneously, quantum oscillations in the magnetic field dependence of the TEP are observed for both configurations below and above the MMT.