Spectroscopy of $NbSe_2$ using Energy-Tunable Defect-Embedded Quantum Dots

T. R. Devidas; Itai Keren; Hadar Steinberg

doi:10.1021/acs.nanolett.1c02177

paper

Spectroscopy of $N b S e_{2}$ using Energy-Tunable Defect-Embedded Quantum Dots

arXiv:2106.03047 · doi:10.1021/acs.nanolett.1c02177

Abstract

Quantum dots have sharply defined energy levels, which can be used for high resolution energy spectroscopy when integrated in tunneling circuitry. Here we report dot-assisted spectroscopy measurements of the superconductor $N b S e_{2}$ , using a van der Waals device consisting of a vertical stack of $g r a p h e n e - M o S_{2} - N b S e_{2}$ . The $M o S_{2}$ tunnel barriers host naturally occurring defects which function as quantum dots, allowing transport via resonant tunneling. The dot energies are tuned by an electric field exerted by a back-gate, which penetrates the graphene source electrode. Scanning the dot potential across the superconductor Fermi energy, we reproduce the $N b S e_{2}$ density of states which exhibits a well-resolved two-gap spectrum. Surprisingly, we find that the dot-assisted current is dominated by the lower energy feature of the two $N b S e_{2}$ gaps, possibly due to a selection rule which favors coupling between the dots and the orbitals which exhibit this gap.

22 pages, 6 figures

Spectroscopy of NbSe2​ using Energy-Tunable Defect-Embedded Quantum Dots

Abstract

References in corpus (7)

Spectroscopy of $N b S e_{2}$ using Energy-Tunable Defect-Embedded Quantum Dots