Lateral imaging of the superconducting vortex lattice using Doppler-modulated scanning tunneling microscopy

TL;DR

This study uses Doppler-modulated scanning tunneling microscopy to spatially image the vortex lattice in a superconductor, revealing stripe patterns and their dependence on magnetic field, and introduces a general method for probing subsurface vortices.

Contribution

It demonstrates a novel application of Doppler-modulated STM to image vortex lattices and analyze superfluid momentum distribution in superconductors.

Findings

Stripe patterns in conductance images vary with magnetic field as H^-0.5

Higher zero-bias conductance regions correspond to lower gap-edge conductance

Method enables probing of subsurface vortices in superconductors

Abstract

By spatially mapping the Doppler effect of an in-plane magnetic field on the quasiparticle tunneling spectrum, we have laterally imaged the vortex lattice in superconducting 2H-NbSe2. Cryomagnetic scanning tunneling spectroscopy was performed at 300 mK on the ab-surface oriented parallel to the field H. Conductance images at zero bias show stripe patterns running along H, with the stripe separation varying as H^-0.5. Regions of higher zero-bias conductance show lower gap-edge conductance, consistent with spectral redistribution by spatially-modulated superfluid momentum. Our results are interpreted in terms of the interaction between vortical and screening currents, and demonstrate a general method for probing subsurface vortices.