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arXiv · 2404.03762

Nernst effect of high-mobility Weyl electrons in NdAlSi enhanced by a Fermi surface nesting instability

Rinsuke Yamada·Takuya Nomoto·Atsushi Miyake·Toshihiro Terakawa·Akiko Kikkawa·Ryotaro Arita·Masashi Tokunaga·Yasujiro Taguchi·Yoshinori Tokura·Max Hirschberger
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Abstract

The thermoelectric Nernst effect of solids converts heat flow to beneficial electronic voltages. Here, using a correlated topological semimetal with high carrier mobility $\mu$ in presence of magnetic fluctuations, we demonstrate an enhancement of the Nernst effect close to a magnetic phase transition. A magnetic instability in NdAlSi modifies the carrier relaxation time on 'hotspots' in momentum space, causing a strong band filling dependence of $\mu$. We quantitatively derive electronic band parameters from a novel two-band analysis of the Nernst effect $S_{xy}$, in good agreement with quantum oscillation measurements and band calculations. While the Nernst response of NdAlSi behaves much like conventional semimetals at high temperatures, an additional contribution $\Delta S_{xy}$ from electronic correlations appears just above the magnetic transition. Our work demonstrates the engineering of the relaxation time, or the momentum-dependent self energy, to generate a large Nernst response independent of a material's carrier density, i.e. for metals, semimetals, and semiconductors with large $\mu$.

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Rinsuke Yamada, Takuya Nomoto, Atsushi Miyake, Toshihiro Terakawa, Akiko Kikkawa, Ryotaro Arita, Masashi Tokunaga, Yasujiro Taguchi, Yoshinori Tokura, Max Hirschberger. 2024-04-04. Nernst effect of high-mobility Weyl electrons in NdAlSi enhanced by a Fermi surface nesting instability. https://doi.org/10.1103/physrevx.14.021012

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