Giant Nernst effect and field-enhanced transversal zNT in ZrTe5

Abstract

Thermoelectric materials can recover electrical energy from waste heat and vice versa, which are of great significance in green energy harvesting and solid state refrigerator. 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 𝑆 𝑥𝑦 (when B//b) approaches 1900 𝜇𝑉/𝐾 at T=100K and B=13T, and the out-of-plane 𝑆 𝑥𝑧 (when B//c) reaches 5000 𝜇𝑉/𝐾. As a critical part of 𝑧 𝑁 𝑇, the linearly increased in-plane 𝑆 𝑥𝑦 and resistivity 𝜌 𝑦𝑦 regard to B induces an almost linear increasing transversal 𝑧 𝑁 𝑇 without saturate under high fields. The maximum 𝑧 𝑁 𝑇 of 0.12 was obtained at B=13 T and T= 120K, which significantly surmounts its longitudinal counterpart under the same condition.

Ultrahigh transverse thermoelectric power factor in flexible Weyl semimetal WTe2

“…Fig. 4a compares the mobility and Nernst thermopower of a few topological materials, including WTe 2 , ZrTe 5 36 , NbP 8 , and Cd 3 As 2 37 , as well as Bi single crystals 29,30 . The Nernst signal strength has a positive correlation with the charge-carrier mobility.…”

“…Fig. 4c summarizes the Nernst PF values of WTe 2 and other topological semimetals, including NbP 8,40 , ZrTe 5 36 and Cd 3 As 2 37 , with a comparison of the Seebeck PF values of most of the wellknown longitudinal thermoelectric semiconductors [41][42][43][44][45][46][47][48][49] . The topological semimetals, particularly WTe 2 , have high PF values, which are even 2-3 orders of magnitude higher than those of the best thermoelectric semiconductors.…”

“…Ribbon-shaped layered crystals with shiny surfaces were obtained. 36 and Cd 3 As 2 37 , and a comparison with the Seebeck power factors of high-performance thermoelectric semiconductors including Bi 1-x Sb x 39 , (Bi,Sb) 2 Te 3 38 , Mg 3 (Bi,Sb) 2 41 , MgAgSb 42 , GeTe 43 , SiGe 44 , CoSb 3 45 , PbTe 46 , SnSe 47 , SnTe 48 , and CuSe 2 49 .…”

“…b temperature dependence of Nernst power factor of WTe 2 , inset shows the zT values. c Nernst power factor of various topological semimetals including NbP 8,40 , ZrTe 536 and Cd 3 As 237 , and a comparison with the Seebeck power factors of high-performance thermoelectric semiconductors including Bi 1-x Sb x 39 , (Bi,Sb) 2 Te 338 , Mg 3 (Bi,Sb) 241 , MgAgSb 42 , GeTe43 , SiGe44 , CoSb 345 , PbTe46 , SnSe 47 , SnTe48 , and CuSe 249 .…”

Ultrafast photothermoelectric effect in Dirac semimetallic Cd3As2 revealed by terahertz emission

“…When a magnetic field in applied, the magnetic field can split a Dirac node into a pair of Weyl nodes with opposite chirality, and then a nonzero Berry curvature is generated. It has been found that the Berry curvature can induce an anomalous Nernst effect to add on the conventional one 6 , 49 – 51 . At low magnetic field and low temperature, it is predicted theoretically that the total Nernst effect is characterized by an almost steplike profile at the low magnetic field and the response is dominated by the anomalous Nernst effect 49 , 50 .…”