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T. R. Devidas (Bar Ilan University, Israel) – Spectroscopy of barrier defects coupled to superconductors in vdW tunneling devices – 26 de Agosto 14:00
26 de agosto:14:00 - 15:00
Superconductor-Quantum Dot (SC-QD) coupling is a subject of an intense research effort. In the van der Waals (vdW) family of materials, atomic defects in insulating/semiconducting materials play the role of Quantum Dots, allowing their easy integration into vertical vdW tunnelling heterostructures. Based on the strength of coupling between the QD and the superconductor, one can observe a multitude of ground states. In the present work, we study two vdW tunneling devices. In the first we study a Graphene/MoS2/NbSe2 vertical heterostructure. The graphene here serves as source electrode that allows for energy tunability of the QD present in MoS2, via an electric field through an electrostatic back-gate. The QD is then observed to serve as a very sensitive spectrometer mapping the NbSe2 density of states. In the second device, which is a MoS2/Graphene/NbSe2 heterostructure, we observe zero-energy Kondo features within the superconducting energy gap of NbSe2. We relate this to the co-existence of Kondo and superconductivity to the availability of charge carriers associated with the low energy band of NbSe2 turning normal.