Tuning Bound States of Symmetry-Breaking Vortices via Unidirectional Charge Density Wave in a Transition-Metal Dichalcogenide Superconductor

TL;DR

This study demonstrates how unidirectional charge density waves in a transition-metal dichalcogenide superconductor can be used to control and manipulate vortex bound states, revealing new possibilities for vortex engineering.

Contribution

It uncovers the modulation of vortex states by unidirectional CDWs in 1T''-NbTe2, a novel platform for vortex control in superconductors.

Findings

Elliptical vortices align with CDW stripes under magnetic fields

CDW domain boundaries cause abrupt vortex state changes

Vortex states can be controlled across CDW nanodomains

Abstract

The interplay between charge density wave (CDW) and superconducting vortex bound states are crucial for fundamental physics of superconductivity and advancing quantum nanotechnologies. However, the CDW-mediated modulation of vortex bound states, which opens up a new platform for vortex engineering, remains unexplored. Here, we report spatially anisotropic vortex states modulated by the unidirectional CDWs in a transition-metal dichalcogenide superconductor 1T''-NbTe2 using ultra-low-temperature scanning tunneling microscopy/spectroscopy. The stripe-like 3x1x3 CDW order exhibits a robust three-dimensional character across step edges and coexists with superconductivity below a critical temperature of 0.4 K. Under out-of-plane magnetic fields, we observe elliptical vortices whose elongation aligns with the CDW stripes, indicating strong coupling between vortex morphology and underlying electronic order. Remarkably, CDW domain boundaries induce abrupt changes in vortex orientation and vortex bound states, enabling controllable vortex states across CDW nanodomains. These findings establish a new pathway for manipulating superconducting vortex bound states via CDW coupling.