Quantum Metal behavior in ultra-clean 2H-NbSe2 devices

Low temperature measurements of few-layer 2H-NbSe2 in the 2D limit at a finite magnetic field exhibit a metallic behavior instead of a superconductor to insulator transition. The physical nature of this phase, known as a quantum metal, is still under debate. In these 2D systems disorder and defects may play a role in understanding the underlying mechanisms, NbSe2 is especially sensitive as it is air-sensitive. Using a novel fabrication technique based on encapsulation with h-BN pre-patterned with metal via contacts, we are able to simultaneously protect the NbSe2 layer and make electrical contact in a single, lithography-free, step. With this technique we fabricate robust and stable devices of high quality with an array of parallel contact to study NbSe2 non-locally. We show that at zero magnetic field we can stabilize a normal-superconducting boundary by sourcing a local current enabling the study of quasi-particle excitations of the superconductor and Andreev processes. At a finite magnetic field our non-local measurement shed light into the nature of the metallic phase by examining the power-law behavior of the resistance with magnetic field. We further compare our results to Time-Dependent-Ginzburg-Landau simulations.