One-Dimensional Edge Transport in Few-Layer WTe₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Topological Materials

Background:

• Tungsten ditelluride (WTe2) is a layered material with predicted higher-order topological insulator (HOTI) properties.
• Identifying and observing one-dimensional (1D) topological states in WTe2 is challenging due to its gapless nature and bulk transport interference.

Purpose of the Study:

• To investigate the Josephson effect in few-layer WTe2 to distinguish between edge and bulk transport.
• To provide evidence for the existence of 1D topological states and confirm WTe2 as a HOTI.

Main Methods:

• Fabrication of few-layer WTe2 devices.
• Measurement of the Josephson effect under varying magnetic fields.
• Analysis of transport properties, including current-phase relation (CPR) and robustness in magnetic fields.

Main Results:

• The Josephson effect measurements revealed the presence of 1D topological states on the edges and steps of few-layer WTe2.
• Observed properties include long-range Josephson transport, remarkable magnetic field robustness, and nonsinusoidal CPR, similar to those in bismuth, another HOTI.
• These characteristics are indicative of topologically protected states.

Conclusions:

• The study strongly suggests that the observed 1D states in few-layer WTe2 are of topological origin.
• The findings confirm that few-layer WTe2 behaves as a higher-order topological insulator (HOTI).
• This work opens avenues for exploring topological phenomena in WTe2-based heterostructures.