The return of the minigap: The delicate issue of a topological gap in semiconductor Majorana wires

Details The return of the minigap: The delicate issue of a topological gap in semiconductor Majorana wires The return of the minigap: The delicate issue of a topological gap in semiconductor Majorana wires

2012-04-16

arxiv.org/abs/1204.3637v2

Physics

Condensed Matter

Mesoscale and Nanoscale Physics

Crucial difference of the present results with previously reported results for idealized spinless p-wave wires discussed (see

Scientific paper

The excitation gap above the Majorana fermion (MF) modes at the ends of 1D topological superconducting (TS) semiconductor wires scales with the bulk quasiparticle gap E_{qp}. This gap, also called minigap, facilitates experimental detection of the pristine TS state and MFs at experimentally accessible temperatures T << E_{qp}. Here we show that the linear scaling of minigap with E_{qp} can fail in quasi-1D wires with multiple confinement bands when the applied Zeeman field is greater than or equal to about half of the confinement-induced bandgap. TS states in such wires have an approximate chiral symmetry supporting multiple near zero energy modes at each end leading to a minigap which can effectively vanish. We show that the problem of small minigap in such wires can be resolved by forcing the system to break the approximate chirality symmetry externally with a second Zeeman field. Although experimental signatures such as zero bias peak from the wire ends is suppressed by the second Zeeman field above a critical value, such a field is required in some important parameter regimes of quasi-1D wires to isolate the topological physics of end state MFs. We also discuss the crucial difference of our minigap calculations from the previously reported minigap results appropriate for idealized spinless p-wave superconductors and explain why the clustering of fermionic subgap states around the zero energy Majorana end state with increasing chemical potential seen in the latter system does not apply to the experimental TS states in spin-orbit coupled nanowires.

Affiliated with

Also associated with

No associations

Rating

The return of the minigap: The delicate issue of a topological gap in semiconductor Majorana wires does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The return of the minigap: The delicate issue of a topological gap in semiconductor Majorana wires, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The return of the minigap: The delicate issue of a topological gap in semiconductor Majorana wires will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-288435