Thermoelectric evidence for high-field anomalies in the hidden order phase of URu₂Si₂

Measurements of the thermoelectric coefficients of URu₂Si ₂ 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 H^*=23 T. We analyze our results in terms of a Lifshitz transition in URu₂Si₂ originating from the hidden order Pauli depairing on a given subband.