Eur. Phys. J. Special Topics 227, 1377–1386 (2018)
https://doi.org/10.1140/epjst/e2018-800093-5

Regular Article

The invisible Majorana bound state at the helical edge

Institute for Theoretical Physics and Astrophysics, University of Würzburg, Am Hubland, 97074 Wurzburg, Germany

^a e-mail: niccolot@gmail.com

Received: 14 May 2018
Received in final form: 22 June 2018
Published online: 17 September 2018

Abstract

The presence of a Majorana bound state in condensed matter systems is often associated to a zero bias peak in conductance measurements. Here, we analyze a system were this paradigm is violated. A Majorana bound state is always present at the interface between a quantum spin Hall system that is magnetically gapped and a quantum spin Hall system gapped by proximity induced s-wave superconductivity. However, the linear conductance could be either zero or non-zero and quantized depending on the energy and length scales of the barriers. The transition between the two values is reminiscent of the topological phase transition in proximitized spin–orbit coupled quantum wires in the presence of an applied magnetic field. We interpret the behavior of the conductance in terms of scattering states at both zero and non-zero energy.