Berezinskii-Kosterlitz-Thouless transition in the type-I Weyl semimetal PtBi$_2$

Arthur Veyrat; Valentin Labracherie; Dima L. Bashlakov; Federico Caglieris; Jorge I. Facio; Grigory Shipunov; Titouan Charvin; Rohith Acharya; Yurii Naidyuk; Romain Giraud; Jeroen van den Brink; Bernd Büchner; Christian Hess; Saicharan Aswartham; Joseph Dufouleur

doi:10.1021/acs.nanolett.2c04297

arXiv · 2101.01620

Berezinskii-Kosterlitz-Thouless transition in the type-I Weyl semimetal PtBi$_2$

Arthur Veyrat·Valentin Labracherie·Dima L. Bashlakov·Federico Caglieris·Jorge I. Facio·Grigory Shipunov·Titouan Charvin·Rohith Acharya·Yurii Naidyuk·Romain Giraud·Jeroen van den Brink·Bernd Büchner·Christian Hess·Saicharan Aswartham·Joseph Dufouleur

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Abstract

Symmetry breaking in topological matter has become in recent years a key concept in condensed matter physics to unveil novel electronic states. In this work, we predict that broken inversion symmetry and strong spin-orbit coupling in trigonal PtBi$_2$ lead to a type-I Weyl semimetal band structure. Transport measurements show an unusually robust low dimensional superconductivity in thin exfoliated flakes up to 126 nm in thickness (with $T_c \sim 275-400$~mK), which constitutes the first report and study of unambiguous superconductivity in a type-I Weyl semimetal. Remarkably, a Berezinskii-Kosterlitz-Thouless transition with $T_\text{BKT} \sim 310$~mK is revealed in up to 60 nm thick flakes, which is nearly an order of magnitude thicker than the rare examples of two-dimensional superconductors exhibiting such a transition. This makes PtBi$_2$ an ideal platform to study low dimensional and unconventional superconductivity in topological semimetals.

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Arthur Veyrat, Valentin Labracherie, Dima L. Bashlakov, Federico Caglieris, Jorge I. Facio, Grigory Shipunov, Titouan Charvin, Rohith Acharya, Yurii Naidyuk, Romain Giraud, Jeroen van den Brink, Bernd Büchner, Christian Hess, Saicharan Aswartham, Joseph Dufouleur. 2021-01-05. Berezinskii-Kosterlitz-Thouless transition in the type-I Weyl semimetal PtBi$_2$. https://doi.org/10.1021/acs.nanolett.2c04297

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