Giant Nernst effect and field-enhanced transversal zNT in ZrTe5

Thermoelectric materials can recover electrical energy from waste heat and vice versa, which are of great significance in green energy harvesting and solid state refrigerators. The thermoelectric figure of merit ( zT ) quantifies the energy conversion efficiency, and a large Seebeck or Nernst effect is crucial for the development of thermoelectric devices. Here we present a significantly large Nernst thermopower in topological semimetal ZrTe5, which is attributed to both strong Berry curvature and bipolar transport. The largest in-plane Sxy (when B//b) approaches 1900 μV / K at T = 100 K and B = 13 T, and the out-of-plane Sxz (when B//c) reaches 5000 μ V / K . As a critical part of zNT, the linearly increased in-plane Sxy and resistivity ρyy in regard to B induces an almost linear increasing transversal zNT without saturation under high fields. The maximum zNT of 0.12 was obtained at B = 13 T and T = 120 K, which significantly surmounts its longitudinal counterpart under the same condition.