Large Nernst power factor over a broad temperature range in polycrystalline Weyl semimetal NbP

Abstract

The discovery of topological materials has provided new opportunities to exploit advanced materials for heat-to-electricity energy conversion as they share many common characteristics with thermoelectric materials.In this work, we report the magneto-thermoelectric properties and Nernst effect of the topological Weyl semimetal NbP. We find that polycrystalline, bulk NbP shows a significantly larger Nernst thermopower than its conventional thermopower under magnetic field. As a result, a maximum Nernst power factor of B35 Â 10 À4 W m À1 K À2 is achieved at 9 T and 136 K, which is 4 times higher than its conventional power factor and is also comparable to that of state-of-the-art thermoelectrics. Moreover, the Nernst power factor maintains relatively large value over a broad temperature range. These results highlight that the enhancement of thermoelectric performance can be achieved in topological semimetals based on the Nernst effect and transverse transport.

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

“…Furthermore, because the electrical resistivity in the ac plane is approximately isotropic [39], the Nernst power factor can be estimated as S xy 2 /ρ (Figure 2(f)). Like the conventional power factor (Figure 1(d)), the Nernst power factor also peaks at approximately 15 K. A maximum value of approximately 90 μW•cm -1 •K -2 is obtained at various magnetic fields, which is approximately 3 times larger than the value obtained in polycrystalline bulk NbP [10].…”

“…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. Large magneto-thermopower and Nernst thermopower were observed in both single crystals and polycrystalline samples [10,16,26]. These findings demonstrate that topological semimetals provide fertile ground for exploring magneticfield-mediated thermoelectric properties.…”

“…When a conductive solid is placed under a longitudinal temperature gradient and a transverse magnetic field, two types of thermoelectric responses occur, i.e., the magneto-Seebeck effect in the longitudinal direction and the Nernst effect in the other transverse direction [9]. Both longitudinal and transverse thermoelectric effects have recently received attention in the studies of topological semimetals, specifically, studies of giant magnetic-field enhancement of the thermoelectric properties [10,11] or exploration of the Berry curvature-related anomalous thermoelectric transport phenomena [12][13][14][15][16][17][18]. 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.…”

Pure Zirconium: Type II Nodal Line and Nodal Surface States

“…Topological semimetals and topological metals (Fang et al, 2016 ; Yan and Felser, 2017 ; Schoop et al, 2018 ; Zhou et al, 2018 ; Gao et al, 2019 ; Hu et al, 2019 ; Klemenz et al, 2019 ; Pham et al, 2019 ; Xie et al, 2019 ; Yi et al, 2019 ) have been widely investigated because they can be regarded as good candidates for use in the areas of spintronics and quantum computers. Weyl and Dirac materials (Ouyang et al, 2016 ; Zhong et al, 2016 ; Zhou et al, 2016 ; Liu et al, 2017 ; Fu et al, 2018 ; Meng et al, 2019 , 2020a ; Zhang et al, 2020 ), which host 2-fold and fourfold degenerate band-crossing points, have been explored in real materials and their exotic properties have been confirmed in experiments. Moving forward, a series of three-dimension materials, with 1D and 2D band crossing points, have been predicted to be nodal line semimetals/metals (Phillips and Aji, 2014 ; Gan et al, 2017 ; Jin et al, 2017 , 2019 , 2020 ; Lu et al, 2017 ; Yang et al, 2017 ; Chen et al, 2018 ; Gao et al, 2018 ; Liu et al, 2018 ) and nodal surface semimetals/metals (Wu et al, 2018 ; Zhang et al, 2018 ; Wang et al, 2020 ), respectively.…”

Realization of Opened and Closed Nodal Lines and Four- and Three-fold Degenerate Nodal Points in XPt (X = Sc, Y, La) Intermetallic Compound: A Computational Modeling Study

“…In the last decade, with the discovery of topological insulators (Cava et al, 2013;Kou et al, 2013;Zhao et al, 2013;Shen and Cha, 2014;Wang et al, 2014;Luo et al, 2015;Zhou et al, 2015;Liu et al, 2016;Chen et al, 2017a;Loïc and Izmaylov, 2017;Pan et al, 2017;Pielnhofer et al, 2017;Politano et al, 2017;Andrey et al, 2018;Hu et al, 2018Hu et al, , 2019Gao et al, 2019;Mal et al, 2019;Qiao et al, 2019;Narimani et al, 2020), topologically non-trivial materials have attracted significant interest in the chemistry, physics, and materials science communities. Recently, studies have increasingly focused on topological semimetals/metals (Bin et al, 2018;Chenguang et al, 2018;Zhou et al, 2018;He et al, 2019He et al, , 2020Jin et al, 2019aJin et al, , 2020bLi et al, 2019;Qie et al, 2019;Xie et al, 2019;Yi et al, 2019;Zhong et al, 2019;Ma and Sun, 2020;Meng et al, 2020b;Wang et al, 2020a,c,d;Yang and Zhang, 2020;Zhang et al, 2020;Zhao et al, 2020) with non-trivial band topology. For example, in 2018, Schoop et al (2018) described the key features of ...…”