Doping as a tuning mechanism for magnetothermoelectric effects to improve $zT$ in polycrystalline NbP

Doping as a tuning mechanism for magnetothermoelectric effects to improve $z T$ in polycrystalline NbP

Eleanor F. Scott, Katherine A. Schlaak, Poulomi Chakraborty, Chenguang Fu, Satya N. Guin, Safa Khodabakhsh, Ashley E. Paz y Puente, Claudia Felser, Brian Skinner, and Sarah J. Watzman

Phys. Rev. B 107, 115108 – Published 3 March 2023

Abstract

Weyl semimetals combine topological and semimetallic effects, making them candidates for interesting and effective thermoelectric transport properties. Here, we present experimental results on polycrystalline NbP, demonstrating the simultaneous existence of a large Nernst effect and a large magneto-Seebeck effect, which is typically not observed in a single material at the same temperature. We compare transport results from two polycrystalline samples of NbP with previously published work, observing a shift in the temperature at which the maximum Nernst and magneto-Seebeck thermopowers occur, while still maintaining thermopowers of similar magnitude. Theoretical modeling shows how doping strongly alters both the Seebeck and Nernst magnetothermopowers by shifting the temperature-dependent chemical potential, and the corresponding calculations provide a consistent interpretation of our results. Thus, we offer doping as a tuning mechanism for shifting magnetothermoelectric effects to temperatures appropriate for device applications, improving $z T$ at desirable operating temperatures. Furthermore, the simultaneous presence of both a large Nernst and magneto-Seebeck thermopower is uncommon and offers unique device advantages if the thermopowers are used additively. Here, we also propose a unique thermoelectric device that would collectively harness the large Nernst and magneto-Seebeck thermopowers to greatly enhance the output and $z T$ of conventional thermoelectric devices.

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Received 30 June 2022
Revised 22 November 2022
Accepted 9 February 2023

DOI:https://doi.org/10.1103/PhysRevB.107.115108

Physics Subject Headings (PhySH)

Doping effects Nernst effect Seebeck effect Thermoelectric effects Thermoelectric generators Thermomagnetic effects Thermopower Topological materials Weyl fermions

Energy Science & TechnologyCondensed Matter, Materials & Applied Physics

Authors & Affiliations

Eleanor F. Scott ¹, Katherine A. Schlaak^1,2, Poulomi Chakraborty ³, Chenguang Fu^4,5, Satya N. Guin^5,6, Safa Khodabakhsh ¹, Ashley E. Paz y Puente¹, Claudia Felser⁵, Brian Skinner³, and Sarah J. Watzman ^1,*

¹Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, Ohio 45221, USA
²Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221, USA
³Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
⁴Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
⁵Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany
⁶Department of Chemistry, Birla Institute of Technology and Science, Pilani–Hyderabad Campus, Hyderabad 500078, India

^*Author to whom all correspondence should be addressed: watzmasj@ucmail.uc.edu

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Issue

Vol. 107, Iss. 11 — 15 March 2023

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