Electrical Step-Edge Contact to a Topological Superconductor Candidate 2M-WS₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Computing

Background:

• Topological superconductors (TSCs) are crucial for hosting Majorana bound states.
• Environmental sensitivity and poor electrical contacts hinder practical applications of 2D TSCs.
• Existing fabrication methods struggle with encapsulation and high-quality contacts for 2D TSCs.

Purpose of the Study:

• To develop a novel contact geometry for encapsulated 2D topological superconductor candidates.
• To achieve low contact resistance and high-quality electrical connections to 2D TSCs.
• To investigate the intrinsic properties of 2M-WS₂ and its potential for electronic devices.

Main Methods:

• Fabrication of encapsulated 2M-WS₂ devices with novel step-edge metal contacts.
• Electrical transport measurements, including critical current (I_C) and differential resistance (dV/dI) analysis.
• Investigation of Andreev reflection to assess TSC-metal interface transparency.

Main Results:

• Achieved exceptionally low contact resistance (down to ~65 Ω·µm for a six-unit device).
• Demonstrated highly transparent TSC-metal interfaces via Andreev reflection.
• Observed twofold rotational symmetry in I_C and anomalous peaks in dV/dI, suggesting multigap superconductivity.

Conclusions:

• The novel step-edge contact geometry overcomes major challenges in 2D TSC device fabrication.
• Encapsulated 2M-WS₂ exhibits intrinsic properties indicative of multigap superconductivity.
• This work paves the way for high-performance topological superconductor-based electronics.