Project Description
With charge-based electronics getting to their limits in storage density, speed and energy consumption, spin-based electronics (spintronics) is now a central research topic and promises significant improvements in device performances. Controlling spins with an electric field is a major goal in spintronics since it is a low-energy-consumption handle to act on a fundamental property of matter.
Taking advantage of the predicted giant Rashba effect at their interfaces, transition metal dichalcogenides (TMDCs) monolayers gated by a ferroelectric oxide layer can achieve this goal. By combining advanced angle- and spin- resolved photoemission spectroscopy, the long-term project behind this thesis aims at a thorough characterization of the spin-split bands of TMDCs deposited on ferroelectric ultrathin films via molecular beam epitaxy or chemical transfer. By focusing on strong spin-orbit-coupled materials and hybrid interfaces, this project falls within the more general field of Quantum Materials, a fascinating venue to uncover the roles of symmetry, topology, dimensionality and strong correlations in macroscopic observables.
The goal of the PhD thesis is to measure the spin texture of the TMDC layer as a function of the ferroelectric polarization of the substrate, in a way compatible with high resolution photoemission spectroscopy experiments. The PhD adviser and his collaborators showed their ability to fabricate TMDCs on the one hand and oxide thin films on the other. They have performed some preliminary experiments showing the feasibility of WS2 transfer on BaTiO3 thin films and measured rough WS2 band structure with minimal surface preparation. The PhD student will develop a reproducible, efficient method to clean in ultra-high vacuum (UHV) the TMDC/ferroelectric interface. In close collaboration with the film growers (C2N Orsay), she or he will monitor the evolution of the ferroelectric and electric properties as a function of annealing time and temperature. Ultimately, the electronic structure of clean samples will be fully characterized using the angle-resolved photoemission spectroscopy (ARPES) setup of the Cassiopée beamline (one week of in-house beamtime per semester is guaranteed). An outstanding achievement would consist in the control of the ferroelectric polarization in UHV and measure of the polarization-dependent spin texture. This thesis is the scientific subject of the ANR JCJC project CORNFLAKE.
The PhD work will be located on the synchrotron SOLEIL site. It will involve numerous collaborations with “Plateau de Saclay” laboratories (C2N, UMR CNRS/THALES) and will require highly motivated students. It will involve several travels for beamtime and conferences.
The PhD thesis is fully funded by the ANR via the project CORNFLAKE.
Training and experiences
Master degree in solid state physics
Team work abilities
Good oral communication and writing skills in English
How to Apply ?
Please send a resume to "pro at juer.fr" or use the SOLEIL
website.