Abstract
Fu and Kane have discovered that a topological insulator with induced s-wave superconductivity (gap Δ0, Fermi velocity v F, Fermi energy μ) supports chiral Majorana modes propagating on the surface along the edge with a magnetic insulator. We show that the direction of motion of the Majorana fermions can be inverted by the counterflow of supercurrent, when the Cooper pair momentum along the boundary exceeds . The chirality inversion is signaled by a doubling of the thermal conductance of a channel parallel to the supercurrent. Moreover, the inverted edge can transport a nonzero electrical current, carried by a Dirac mode that appears when the Majorana mode switches chirality. The chirality inversion is a unique signature of Majorana fermions in a spinful topological superconductor: it does not exist for spinless chiral p-wave pairing.
Highlights
The chiral edge modes of the quantum Hall effect in a semiconductor have a superconducting analogue [1]: a two-dimensional (2D) superconductor with broken time-reversal symmetry and broken spin-rotation symmetry can enter a phase in which the gapped interior supports gapless edge excitations
In this work we propose an electrical signature of a chiral edge mode, triggered by the chirality inversion when a supercurrent flows along the boundary
We have reported on a manifestation of the Doppler effect from a supercurrent in a spinful topological superconductor: a supercurrent flowing along the magnetic boundary of a Fu–Kane superconductor can reverse the chirality of the Majorana edge mode, without closing the bulk gap
Summary
Keywords: topological superconductors, Majorana edge modes, Doppler shift, chiral edge modes, quantum transport Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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