Tunneling into the vortex state of NbSe${}_2$ with van der Waals junctions

Abstract

We have performed device-based tunnelling spectroscopy of NbSe${}_2$ in the vortex state with a magnetic field applied both parallel and perpendicular to the $a-b$ plane. Our devices consist of layered semiconductors placed on top of exfoliated NbSe${}_2$ using the van der Waals transfer technique. At zero field, the spectrum exhibits a hard gap, and the quasiparticle peak is split into low and high energy features. The two features, associated with the effective two-band nature of superconductivity in NbSe${}_2$, exhibit markedly distinct responses to the application of magnetic field, suggesting an order-of-magnitude difference in the spatial extent of the vortex cores of the two bands. At energies below the superconducting gap, the hard gap gives way to vortex-bound Caroli-de Gennes-Matricon states, allowing the detection of individual vortices as they enter and exit the junction. Analysis of the sub-gap spectra upon application of parallel magnetic field allows us to track the process of vortex surface formation and spatial rearrangement in the bulk.

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• Superconductivity in twisted Graphene $\mathrm{NbS}{\mathrm{e}}_2$ heterostructures
• van der Waals heterostructures based on atomically-thin superconductors
• Van der Waals heterostructures with spin-orbit coupling
• Spectroscopy of $NbS{e}_2$ using Energy-Tunable Defect-Embedded Quantum Dots
• Multi-Band Superconductivity in Strongly Hybridized 1T'-WTe${}_2$/NbSe${}_2$ Heterostructures
• Chip-Integrated Vortex Manipulation
• Quantum-Dot Assisted Spectroscopy of Degeneracy-Lifted Landau Levels in Graphene
• Protocol for reading out Majorana vortex qubit and testing non-Abelian statistics
• FeTe${}_{0.55}$Se${}_{0.45}$ van der Waals Tunneling Devices
• Kondo Effect in Defect-bound Quantum Dots Coupled to NbSe${}_2$
• Giant Thermoelectric Response of Fluxons in Superconductors
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