Gapless Andreev bound states in a topological junction on the Quantum Spin Hall insulator HgTe
Mardi 27 septembre 2016 15:00
- Duree : 1 heure
Lieu : Salle "Remy Lemaire" K 223 (1er étage) bât. K de l’institut Néel/CNRS
Orateur : Erwann BOCQUILLON (Laboratoire Pierre Aigrain, Paris)
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Two dimensional topological insulators coupled to superconducting and ferromagnetic electrodes are a candidate system for the realization of Majorana fermions. Majorana physics has recently attracted considerable attention in both theoretical and experimental studies due to the prospects for new physics stemming from non-Abelian exchange statistics and the associated applications to topological quantum computation. However, experimental studies unveiling the interplay between superconductivity and topological electronic transport remain scarce.
Here we report the observations of signatures of topological superconductivity induced in a HgTe quantum well, a system that exhibits the quantum spin Hall effect. Namely, we observe the
fractional Josephson effect, in two different manners. When an rf excitation is applied, a doubling of the Shapiro steps is observed [1]. Besides, a clear emission line can be detected at half the
Josephson frequency under dc voltage bias conditions [2]. Both features appear more clearly when the sample is gated towards the quantum spin Hall regime, in a regime where the current
flows mostly along the edges of the device. These signatures thus strongly point towards induced topological superconductivity in the quantum spin Hall edge states.
[1] E. Bocquillon et al., Nature Nanotechnology 10.1038/nnano.2016.159
[2] R.S. Deacon et al., arXiv 1603.09611
Contact : benjamin.sacepe@grenoble.cnrs.fr
Discipline évènement : (Physique)
Entité organisatrice : (Fondation Nanosciences)
Nature évènement : (Séminaire)
Evènement répétitif : (Séminaire Nanoélectronique Quantique)
Site de l'évènement : Polygone scientifique
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