$4\pi$ periodic Andreev bound states in a Dirac semimetal

Chuan Li; Jorrit C. de Boer; Bob de Ronde; Shyama V. Ramankutty; Erik van Heumen; Yingkai Huang; Anne de Visser; Alexander A. Golubov; Mark S. Golden; Alexander Brinkman

doi:10.1038/s41563-018-0158-6

arXiv · 1707.03154

$4\pi$ periodic Andreev bound states in a Dirac semimetal

Chuan Li·Jorrit C. de Boer·Bob de Ronde·Shyama V. Ramankutty·Erik van Heumen·Yingkai Huang·Anne de Visser·Alexander A. Golubov·Mark S. Golden·Alexander Brinkman

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Abstract

Electrons in a Dirac semimetals possess linear dispersion in all three spatial dimensions, and form part of a developing platform of novel quantum materials. Bi$_{1-x}$Sb$_x$ supports a three-dimensional Dirac cone at the Sb-induced band inversion point. Nanoscale phase-sensitive junction technology is used to induce superconductivity in this Dirac semimetal. Radio frequency irradiation experiments reveal a significant contribution of 4$\pi$-periodic Andreev bound states to the supercurrent in Nb-Bi$_{0.97}$Sb$_{0.03}$-Nb Josephson junctions. The conditions for a substantial $4\pi$ contribution to the supercurrent are favourable because of the Dirac cone's topological protection against backscattering, providing very broad transmission resonances. The large g-factor of the Zeeman effect from a magnetic field applied in the plane of the junction, allows tuning of the Josephson junctions from 0 to $\pi$ regimes.

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Chuan Li, Jorrit C. de Boer, Bob de Ronde, Shyama V. Ramankutty, Erik van Heumen, Yingkai Huang, Anne de Visser, Alexander A. Golubov, Mark S. Golden, Alexander Brinkman. 2017-07-11. $4\pi$ periodic Andreev bound states in a Dirac semimetal. https://doi.org/10.1038/s41563-018-0158-6

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