Lifshitz Transition and Metamagnetism: Thermoelectric Studies of CeRu$_2$Si$_2$

TL;DR

This study investigates the thermoelectric power in CeRu$_2$Si$_2$ across its metamagnetic transition, revealing anomalies linked to Fermi surface topology changes and quantum oscillations, enhancing understanding of heavy fermion systems.

Contribution

It provides detailed thermoelectric measurements across the metamagnetic transition, highlighting Fermi surface topology changes and quantum oscillations in CeRu$_2$Si$_2$, a heavy fermion compound.

Findings

Strong TEP anomalies at the metamagnetic transition

Cascade of anomalies at low temperature indicating Fermi surface changes

Observation of quantum oscillations in TEP

Abstract

We report field and temperature dependent measurements of the thermoelectric power (TEP) across the pseudo-metamagnetic transition (MMT) in CeRu$_2$Si$_2$. 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 H$_m$=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.