Missions

The postdoctoral researcher will be responsible for preparing 2D superconducting gases on the surface of KTaO₃ single crystals coated with an ultrathin layer of aluminum, and for characterizing their electronic and structural properties using low-temperature scanning tunneling microscopy (STM).

Activités

The postdoc will carry out surface preparations by depositing aluminum and performing annealing under ultra-high vacuum (UHV). The samples will then be studied using low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES). Subsequently, the postdoc will characterize the sample surfaces using variable-temperature STM. After initial characterizations, scanning tunneling spectroscopy (STS) will be conducted to determine the electronic structure of the 2D gases. Particular attention will be paid to characterizing the band structure, especially the Rashba spin-orbit coupling. The superconducting gap will then be studied as a function of temperature, along with vortex lattices under magnetic fields. Special attention will be given to characterizing spatial fluctuations of the superconducting state.
Once these studies have been completed for various aluminum layer thicknesses, similar experiments will be conducted by replacing aluminum with europium, with the goal of inducing topological superconductivity by coupling a Rashba superconductor with a ferromagnetic insulator.
caractérisations effectuées, le postdoc procédera à des mesures de spectroscopie tunnel à balayage pour déterminer la structure électronique des gaz 2D. Il cherchera en particulier à caractériser la structure de bande t plus particulièrement le couplage spin-orbite Rashba. Il étudiera ensuite le gap supraconducteur en fonction de la température et les réseaux de vortex sous champ magnétique. Une attention particulière sera portée à la caractérisation des fluctuations spatiales de l'état supraconducteur.
Une fois l'ensemble de ces tâches réalisées en fonction de l'épaisseur de la couche d'aluminium, le postdoc procédera aux mêmes études en remplaçant l'aluminium par de l'europium afin d'essayer d'induire de la supraconductivité topologique en couplant un supraconducteur Rashba à un isolant ferromagnétique.

Compétences

The postdoc should have significant experience in surface physics under UHV conditions. Excellent technical skills are expected due to the complexity of the experimental setups developed in the laboratory. Knowledge of scanning probe microscopy and photoemission spectroscopy would be a valuable asset.

Contexte de travail

The research team operates four UHV systems that combine preparation and growth chambers with STM microscopes. Several of the instruments have been custom-designed in-house and require ongoing technical development and maintenance, in which the postdoc will be expected to participate.