Thermoelectric evidence for high-field anomalies in the hidden order phase of URuSi

Malone, L.*; Matsuda, Tatsuma; Antunes, A.*; Knebel, G.*; Taufour, V.*; Aoki, Dai*; Behnia, K.*; Proust, C.*; Flouquet, J.*

Measurements of the thermoelectric coefficients of URuSi in a high magnetic field could imply topological Fermi surface changes even deep inside the hidden order state. A change is observed in the thermopower as a function of the field applied parallel to the easy axis of magnetization, which could signify a change in the Fermi surface characteristics. The maximum of the thermopower coincides with previously measured anomalies in resistivity at = 23T. We analyze our results in terms of a Lifshitz transition in URuSi originating from the hidden order Pauli depairing on a given subband.