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4π-periodic Andreev bound states in a Dirac semimetal

DOI: 10.1038/s41563-018-0158-6

Authors: Chuan Li (University of Twente) , Jorrit C. De Boer (University of Twente) , Bob De Ronde (University of Twente) , Shyama V. Ramankutty (University of Amsterdam) , Erik Van Heumen (Van der Waals–Zeeman Institute, IoP, University of Amsterdam) , Yingkai Huang (Van der Waals–Zeeman Institute, IoP, University of Amsterdam) , Anne De Visser (Van der Waals–Zeeman Institute, IoP, University of Amsterdam) , Alexander A. Golubov (University of Twente; Moscow Institute of Physics and Technology) , Mark Golden (Van der Waals–Zeeman Institute, IoP, University of Amsterdam) , Alexander Brinkman (University of Twente)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Materials , VOL 17 , PAGES 875 - 880

State: Published (Approved)
Published: October 2018
Diamond Proposal Number(s): 12969 , 16433

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.

Journal Keywords: fractional Josephson effect, 4pi Andreev bound states, topological superconductivity, 3D Dirac semi metal, ARPES, Majorana

Subject Areas: Physics, Materials, Information and Communication Technology

Instruments: I05-ARPES