Crossover from Conventional to Unconventional Superconductivity in 2M-WS₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Topological superconductivity is a frontier in condensed matter physics, with potential applications in quantum computing.
• The interplay between bulk and topological surface states (TSSs) is key to achieving topological superconductivity.
• 2D materials offer unique platforms to explore such phenomena due to their reduced dimensionality.

Purpose of the Study:

• To investigate the influence of sample thickness on superconducting properties in 2M-phase WS2.
• To elucidate the transition from conventional to unconventional superconductivity in thin 2D materials.
• To explore the role of TSSs in thickness-dependent superconductivity.

Main Methods:

• Fabrication of 2M-phase WS2 samples with varying thicknesses.
• Transport measurements including critical temperature, critical current, and carrier density.
• Determination of in-plane upper critical fields and analysis of their correlation with carrier density.

Main Results:

• A thickness-dependent transition from conventional to unconventional superconductivity was observed in 2M-WS2.
• Thick samples exhibited conventional superconductivity limited by the Pauli limit.
• Thin samples (<20 nm) showed enhanced in-plane critical fields, inversely correlated with 2D carrier density, indicating unconventional superconductivity.

Conclusions:

• Sample thickness critically influences superconducting behavior and the emergence of unconventional superconductivity in 2D materials.
• The findings highlight the importance of controlling dimensionality for accessing topological superconducting states.
• This study provides crucial insights for future research into topological superconductivity in 2D systems.