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arXiv · 2404.08067

High thermoelectric power factor through topological flat bands

Fabian Garmroudi·Illia Serhiienko·Simone Di Cataldo·Michael Parzer·Alexander Riss·Matthias Grasser·Simon Stockinger·Sergii Khmelevskyi·Kacper Pryga·Bartlomiej Wiendlocha·Karsten Held·Takao Mori·Ernst Bauer·Andrej Pustogow
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Abstract

Thermoelectric (TE) materials are useful for applications such as waste heat harvesting or efficient and targeted cooling. While various strategies towards superior thermoelectrics through a reduction of the lattice thermal conductivity have been developed, a path to enhance the power factor is pressing. Here, we report large power factors up to 5 mW m$^{-1}$ K$^{-2}$ at room temperature in the kagome metal Ni$_3$In$_{1-x}$Sn$_x$. This system is predicted to feature almost dispersionless flat bands in conjunction with highly dispersive Dirac-like bands in its electronic structure around the Fermi energy $E_\text{F}$ [L. Ye et al., Nature Physics 1-5 (2024)]. Within this study, we experimentally and theoretically showcase that tuning this flat band precisely below $E_\text{F}$ by chemical doping $x$ boosts the Seebeck coefficient and power factor, as highly mobile charge carriers scatter into the flat-band states. Our work demonstrates the prospect of engineering extremely flat and highly dispersive bands towards the Fermi energy in kagome metals and introduces topological flat bands as a novel tuning knob for thermoelectrics.

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Fabian Garmroudi, Illia Serhiienko, Simone Di Cataldo, Michael Parzer, Alexander Riss, Matthias Grasser, Simon Stockinger, Sergii Khmelevskyi, Kacper Pryga, Bartlomiej Wiendlocha, Karsten Held, Takao Mori, Ernst Bauer, Andrej Pustogow. 2024-04-11. High thermoelectric power factor through topological flat bands. https://arxiv.org/abs/2404.08067

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