Magnetic Field‐Enhanced Thermoelectric Performance in Dirac Semimetal Cd₃As₂ Crystals with Different Carrier Concentrations

Abstract

The magneto‐thermoelectric figure of merit (ZT) in crystals of the topological Dirac semimetal Cd3As2 with different carrier concentrations is studied. The ZTs for all the crystals increase with the temperature and show maxima at high temperatures. Meanwhile, the temperatures corresponding to the ZT maxima increase with the carrier concentration. The limit to the improvement in ZT(T) at high temperature could be related to the unusual large enhancement in thermal conductivity at elevated temperatures. The bipolar effect and Dirac liquid behavior are presented as processes possibly responsible for the peculiar behavior of the thermal conductivity. Applying a transverse magnetic field initially leads to a dramatic enhancement and, subsequently, to a slight reduction in ZT for all the crystals. The maximum ZT achieved in a magnetic field increases with the carrier concentration and reaches 1.24 at 450 K in a magnetic field of 9 T for the crystal with the highest carrier concentration. It is expected that this work will be beneficial to the current interests in optimizing the thermoelectric properties of quantum topological materials.

Thermoelectric Properties of Novel Semimetals: A Case Study of YbMnSb2

“…d) Comparison of thermopower and power factor of several topological semimetals to high‐performance thermoelectric semiconductors at 300 K. To avoid the influence of other mechanisms, all the data are taken from single crystals without further doping or alloying. [ 29–40 ]…”

“…d) Comparison of thermopower and power factor of several topological semimetals to high-performance thermoelectric semiconductors at 300 K. To avoid the influence of other mechanisms, all the data are taken from single crystals without further doping or alloying. [29][30][31][32][33][34][35][36][37][38][39][40] state-of-the-art Bi 2 Te 3 thermoelectric material which has υ s of 2147 and 2070 m s −1 , along the ab-plane and the c-axis, respectively. [54] This low value of sound velocity, which is generally related to the weak chemical bonding, is one of the reasons leading to the intrinsically low lattice thermal conductivity of YbMnSb 2 .…”

“…To further demonstrate the potential of the unique band structure in YbMnSb 2 for thermoelectrics, we compare the thermopower (|α|) and power factor of YbMnSb 2 to other topological semimetals, including HgTe, [ 32 ] TaAs, [ 33 ] NbP, [ 34,35 ] Cd 3 As 2 , [ 36,37 ] ZrSiS, [ 38,39 ] Co 3 Sn 2 S 2 , [ 40 ] as well as the good thermoelectric semiconductors, for example, Bi 2 Te 3 , [ 41 ] Mg 3 Sb 2 , [ 42 ] and Yb 14 MnSb 11 , [ 43 ] as shown in Figure 3d. Generally, topological semimetals show a smaller |α| than that of thermoelectric semiconductors.…”

Magnetic Topological Semimetal Phase with Electronic Correlation Enhancement in SmSbTe

“…Topological materials are a promising platform for a wide range of next‐generation technologies. [ 1–16 ] In topological Dirac or Weyl semimetals, symmetry‐protected Dirac or Weyl nodes host relativistic fermions with low‐energy excitations that can be described by Dirac or Weyl equations, respectively. [ 4,5 ] In addition, topological nodal‐line semimetals exhibiting linear band crossings along a 1D loop have also been discovered.…”

Largely Suppressed Magneto-Thermal Conductivity and Enhanced Magneto-Thermoelectric Properties in PtSn 4

“…For instance, in the Dirac semimetal Cd 3 As 2 [19], which has ultrahigh carrier mobility [20], anomalous magneto-Seebeck and Nernst effects were recently observed [12,14], and the relationship between these anomalous transport properties with Berry curvature was discussed. Moreover, the magnetic-field-induced giant enhancement in both longitudinal and transverse zT values were found in Cd 3 As 2 single crystals near room temperature [11,21,22]. NbP, one of the first type-I Weyl semimetals to be discovered [23][24][25], has recently attracted attention as a material platform for exploring the Weyl physics-related thermoelectric transport properties.…”