Orateur
Description
In the current quest of innovative materials which combine two-dimensionality, strong spin-orbit, valley physics, superconductivity, charge density waves, quantum-spin Hall effect, the transition metal dichalcogenides (TMD) misfit materials appear as extremely promising. They are constituted by sandwiching rocksalt layers, such as LaSe, and TMD layers such as NbSe$_2$. A very large combination of materials is achievable by playing on the stacking. TMD misfits are a new platform that allows achieving unprecedented high doping levels in TMD materials [1,2]. We will show how we have succeeded adjusting finely the chemical potential over a very wide range in NbSe2 using a Pb$_x$La$_{1-x}$ rocksalt [2], and how this can used for stabilizing several charge density wave orders (2 × 2, 3 × 3, √3 × √3) and tuning the superconducting transition temperature over a wide range. Superconductivity in these compounds exhibits a huge in- plane critical field which is much higher than the paramagnetic limit [3,4] due to a very strong Ising spin-orbit coupling. It was predicted that this huge spin-orbit coupling could lead to non-conventional chiral superconductivity. We will show some hint of a topological superconducting transition in the misfit compounds: on one side of the transition, we observe a conventional s-wave superconductivity immune to disorder, while, on the other side, we observe a fragile superconductivity that exhibits in-gap edge states at step-edges.
References:
[1] R.T. Leriche et al. Advanced Functional Materials 31, 2007706 (2021).
[2] L. Zullo, G. Marini, T. Cren, M. Calandra. Nano Letters 23, 6658 (2023).
[3] P. Samuely et al. Phys. Rev. B 104, 224507 (2021).
[4] T. Samuely et al. Physical Review B 108, L220501 (2023).