Contact

    Johannes Gooth, Dr.
    Phone: +49 351 4646-3003
    Claudia Felser, Prof. Dr.
    Phone: +49 351 4646-3004
    Fax: +49 351 4646-3002
    Tobias Meng, Dr.
    Phone: +49 351 463-33851

    Anomalous thermal transport in topological semimetals

    Topological materials have been proven essential to discover analogues of fermionic elementary particles and to test fundamental laws predicted in high-energy physics. These phenomena come with exotic electrical and thermoelectrical transport properties, such as negative magneto-transport-coefficients, that allow to probe novel quantum effects like the chiral or the mixed axial-gravitational anomaly. While experimental evidence of quantum anomalies in charge transport have recently been observed, we aim to find signatures of quantum anomalies in the thermal transport of Weyl and Dirac semimetals

    Theory predicts that Weyl and Dirac-metals to exhibit quantum anomalies in magneto-thermal transport phenomena, such as in the magneto-thermal conductivity and in the thermal Hall effect. Finding concrete evidence for this hallmark for the first time is the main goal of this project. The project will involve learning to master thermal and electrical transport device fabrication and measurements at cryogenic temperatures and high magnetic fields (up to 14 T). We will work in strong cooperation with a theory group.

    <p><strong>a</strong>, In a strong magnetic field, the Weyl nodes quantize into Landau levels. The lowest Landau levels exhibit a linear dispersion with distinct chirality (±<em>χ</em>). Parallel electric (<strong><em>E</em></strong>) and magnetic (<strong><em>B</em></strong>) fields pump chiral charges from one cone into the other, which breaks chiral symmetry. <strong>b</strong>, Magneto-conductance without zero-field contributions (Δ<em>G</em>) at selected temperatures (see colour scale), for <strong><em>E</em></strong> ∥ <strong><em>B</em></strong>. <strong>c</strong>, Δ<em>G</em> versus |<strong><em>B</em></strong>| for different angles <em>φ</em> (colour scale) between the electric and magnetic fields (see inset), at <em>T</em> = 300 K. <strong>d</strong>, Angular dependence of Δ<em>G</em> at <em>T</em> = 300 K, for varying magnetic field strength (colour scale).</p>
<p align="right">J. Gooth <em>et al., </em>Nature <strong>547</strong>, 324–327 (2017)</p> Zoom Image

    a, In a strong magnetic field, the Weyl nodes quantize into Landau levels. The lowest Landau levels exhibit a linear dispersion with distinct chirality (±χ). Parallel electric (E) and magnetic (B) fields pump chiral charges from one cone into the other, which breaks chiral symmetry. b, Magneto-conductance without zero-field contributions (ΔG) at selected temperatures (see colour scale), for EB. c, ΔG versus |B| for different angles φ (colour scale) between the electric and magnetic fields (see inset), at T = 300 K. d, Angular dependence of ΔG at T = 300 K, for varying magnetic field strength (colour scale).

    J. Gooth et al., Nature 547, 324–327 (2017)

     
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