Resumé / Abstract :

Majorana quasiparticles have generated years of intense research following the first observation of zero-bias anomalies in semiconductor-superconductor heterostructures 1 due to the promises they hold in the field of quantum computing. However, despite these efforts, definitve proofs of the topological nature of these excitations are still being sought after. In particular, one of the most significative prediction for Majorana fermions is that the zero-bias anomalies are to be found at both sides of a wire. Performing a simultaneous conductance measurements at both sides of a wire would be a significative step forward allowing us to verify this theoretical prediction. Unfortunately, usual InAs nanowires are grown on a substrate before being transferred onto another chip before being processed, which prevents from defining a well-defined electrical ground without defects in the center of the wire. An alternative to these standing wires are the so-called SAG 2 (selective area growth) w ires that grow directly on a chip that can be directly processed and can be connected electronically through the epitaxial Al thin film deposited in MBE. Using this technique, we realized three-terminals nanowire structures allowing us to probe both sides of the same wire simultaneously 3,4. In this presentation, I will discuss the advantage of this SAG wires and present results we obtained in these systems in relation to topological signatures as well as future possible developments using this technique.

1 V. Mourik et al., Science 336, 1003 (2012)

2 S. Vaitiekenas et al., Phys. Rev. Lett. 121, 147701 (2018)

3 G. Anselmetti et al., arXiv:1908.05549 (2019)

4 G. Ménard et al., arXiv:1905.05505 (2019)

Contact : equipe-seminaires-nano@listes.grenoble.cnrs.fr