Josephson junction detectors for Majorana modes and Dirac fermions

M. Maiti; K. V. Kulikov; K. Sengupta; Yu. M. Shukrinov

doi:10.1103/PhysRevB.92.224501

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Josephson junction detectors for Majorana modes and Dirac fermions

M. Maiti, K. V. Kulikov, K. Sengupta, Yu. M. Shukrinov

DOI 10.1103/PhysRevB.92.224501 · Physical Review B

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Abstract

We demonstrate that the current-voltage (I−V) characteristics of resistively and capacitively shunted Josephson junctions (RCSJs) hosting localized subgap Majorana states provide a phase-sensitive method for their detection. The I−V characteristics of such RCSJs, in contrast to their resistively shunted counterparts, exhibit subharmonic odd Shapiro steps. These steps, owing to their subharmonic nature, exhibit qualitatively different properties compared to harmonic odd steps of conventional junctions. In addition, the RCSJs hosting Majorana bound states also display an additional sequence of steps in the devil's staircase structure seen in their I−V characteristics; such a sequence of steps makes their I−V characteristics qualitatively distinct from that of their conventional counterparts. A similar study for RCSJs with graphene superconducting junctions hosting Dirac-like quasiparticles reveals that the Shapiro step width in their I−V curves bears a signature of the transmission resonance phenomenon of their underlying Dirac quasiparticles; consequently, these step widths exhibit a π periodic oscillatory behavior with variation of the junction barrier potential. We discuss experiments which can test our theory.