Optical probe of Moiré engineered 2D superconducting materials

Transition metal dichalcogenides (TMDs) have recently attracted significant interest because they allow the exploration of novel quantum phenomena down to the 2D limit. Of particular interest for the present project are metallic TMD like NbSe₂ which displays various quantum phases like Superconductivity (SC) and charge density wave (CDW) states. In addition, the possibility of creating Van der Waals heterostructures (VdW) by vertically stacking 2D materials provide a fertile playground to engineer novel properties and devices. Of particular interest are the Moiré patterns due to the lattice mismatch and crystalline misalignment between vertically stacked layers. Indeed, quantum interference effects between sheets of the 2D TMD with a twist angle allows an unprecedented control of the effective electron kinetic energy scale, driving the system to an interaction dominated regime and drastically enhancing anisotropies, thus providing a pathway to engineer SC properties at the 2D scale.

During the internship, the student will initiate the fabrication of TMD-based VdW heterostructures displaying SC properties using exfoliation techniques. Samples of NbSe₂ will be fabricated and characterized as a function of thickness and twist angle. The obtained samples will be first measured by transport measurements to assess their presence of SC and its critical temperature. Going beyond traditional transport measurements, an originality of the project will be the use of low temperature spectroscopic techniques with micron-size spatial resolution like Raman scattering to probe the SC state.

Contact: Yann Gallais