Early Stage Researcher 11, CTH, SWEDEN


Project title and work package:

Transport properties of a hybrid Topological Insulator – superconductor device, work package Electron transport in reduced dimensionality.



Your aim is to emulate topological superconductivity in TIs via the proximity effect in hybrid structures using s-wave (Al and Nb) superconductors. Topological superconductors are predicted to host Majorana fermions and are therefore very promising candidates for topologically protected Quantum Information processing.

You will study the topologically protected surface electronic state of the TI via the Josephson Effect. For this purpose, you will use nanowires and flakes of Bi2Te3 and Bi2Se3. In order to have a strong Josephson current signal from the bound state (single mode), you will interface the TI nanowires with large gap superconductors such as Nb. In detail, you will be looking for a transition from a 3D to a 2D topological insulator by thinning down the as-grown flakes and nanowires. Such a transition will be detected by a distinct change in the magnetic field response of the Josephson current. Indeed, in 2D TIs the Josephson current will be only carried by the 1D edge states, which results in SQUID-like magnetic field response opposite to a Fraunhofer-like dependence for a 3D TI junction. Moreover, you will integrate the S-TI-S junction, where the TI is in the 2D limit, in a superconducting resonator (collaboration with Early Stage Researcher 14, RAITH, Germany) and perform spectroscopic characterisation of the Andreev bound states localised at the edges. You will explore in collaboration with Early Stage Researcher 4 (AALTO, Finland) the possibility of using S-TI-S hybrid structures for proximity supercurrent detection in thermometry applications at ultra-low temperatures.


Expected Results:

- Observation of unconventional zero-energy bound states in the Josephson transport.

- Spectroscopic features of a topological junction transmon.


Planned secondments:

at UKON, Germany (1 month, Year 1) for training in scanning probe microscopy and study of local electrical transport, at AALTO, Finland (1 month, Year 2) for training in non-equilibrium transport characterisation of S-TI-S hybrid structures, at GRA SEMI, Spain (2 months, Year 2) for training in 2D-materials integration.




Online application deadline set to January 31