Nanoscale devices with superconducting electrodes to locally channel current in 3D Weyl semimetals

TL;DR

This paper presents a novel nanofabrication method using superconducting electrodes on Weyl semimetals, enabling detailed transport measurements and reducing current jetting effects in 3D quantum materials.

Contribution

The authors develop a fabrication technique for nanoscale devices on Weyl semimetals with superconducting electrodes, improving measurement precision and applicability to various materials.

Findings

Demonstrated negative magnetoresistance as a function of angle.

Observed three distinct oscillation frequencies at the Fermi level.

Identified weak anti-localization dip near zero magnetic field.

Abstract

We report on the fabrication of nano-devices on the \hkl[-1 0 1] surface of a Weyl semimetal, a macroscopic crystal of TaAs, and low-temperature transport measurements. We can implement electron beam lithography by peeling off and transferring the resist for nanofabrication onto the irregular crystal. We fabricate the device electrodes with superconducting Niobium nitride (NbN) to control the current flow through the intended active area of the devices. Our device structure enables the reduction of the current jetting effect, and we demonstrate the negative magnetoresistance measurement as a function of angle. The high field magnetotransport show three distinct oscillation frequencies corresponding to the three bands at the Fermi level. Resistance measured in the low magnetic field shows the usual weak anti-localization dip near the zero-field -- a signature of a Weyl material. Our method of fabricating devices with superconducting electrodes provides a way to probe the electrical properties of macroscopic single crystals at the nanoscale. As we use conventional lithographic techniques for patterning, this method can be extended to a wide gamut of electrode materials and a large class of 3D quantum materials.