General Scope: Quantum materials are a class of systems whose electronic or magnetic properties are governed by quantum effects, manifesting up to the macroscopic scale, not just at the atomic level. Prominent examples are superconductivity, magnetic spin liquids, or materials where topological properties of the band structure trigger the emergence of novel ground states. In this project we want to develop a new low temperature instrumentation, which will allow to purposely tune the interactions in such materials by uniaxial stress.
Subject: In this master thesis project, we will set up a probe for uniaxial strain measurements. We will use a commercial uniaxial strain device (Razorbill CS 100) that allows in-situ tensile and compressive strain tuning. It will be installed on a standard Quantum Design PPMS, which allows measurements at temperatures down to 1.8 K and magnetic fields up to 9 T. The newly developed probe will be set up for electrical magneto-transport and hall measurements. To perform stress
measurements, a major task is to prepare well-polished thin bar shaped crystals of appropriate dimensions (the typical sample dimensions are 2mm x 0.2mm x 0.1mm), and to fix the sample on the device. First test measurements will be performed on cerium-based heavy fermion superconductors or antiferromagnets (CeCoIn5 and CeRhIn5) where large single crystals are available in the lab. In a future step we want to use this technique to study uranium-based spin triplet superconductors.
Environment and collaborations: At the IMAPEC team of Pheliqs in CEA, we study different quantum materials under extreme conditions: low temperature, high magnetic fields and high hydrostatic pressure. Research on topological superconductivity in strongly correlated uranium compounds is the central research activity of our team with recently a strong focus on UTe2, which is a spin-triplet superconductor with multiple superconducting phases. IMAPEC has strong interactions with the high magnetic field laboratory LNCMI Grenoble, and this novel technique of uniaxial stress will open new perspectives for high-field measurements in future. The candidate will further profit from strong theoretical support from the theory group of Pheliqs, and have the possibility to interact with groups in Japan where tight collaborations are well established.
Required skills: The candidate should have sound knowledge in solid state physics, good practical skills and strong interest in the development of instrumentation. The subject can be continued by a PhD thesis.