Crossover from Conventional to Unconventional Superconductivity in 2M-WS2

• Published in: arXiv.org 2024-12
• Main Authors: Samarawickrama, Piumi, McBride, Joseph, Sabin, Gautam, Fu, ZhuangEn, Watanabe, Kenji, Taniguchi, Takashi, Wang, Wenyong, Tang, Jinke, Ackerman, John, Leonard, Brian M, Tian, Jifa
• Format: Article
• Language: English
• Subjects: Carrier density; Critical current (superconductivity); Critical field (superconductivity); Current carriers; Superconductivity; Thickness; Topological superconductors; Unconventional superconductivity
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2412.06612

Leveraging reciprocal-space proximity effect between superconducting bulk and topological surface states (TSSs) offers a promising way to topological superconductivity. However, elucidating the mutual influence of bulk and TSSs on topological superconductivity remains a challenge. Here, we report pioneering transport evidence of a thickness-dependent transition from conventional to unconventional superconductivity in 2M-phase WS2 (2M-WS2). As the sample thickness reduces, we see clear changes in key superconducting metrics, including critical temperature, critical current, and carrier density. Notably, while thick 2M-WS2 samples show conventional superconductivity, with an in-plane (IP) upper critical field constrained by the Pauli limit, samples under 20 nm exhibit a pronounced IP critical field enhancement, inversely correlated with 2D carrier density. This marks a distinct crossover to unconventional superconductivity with strong spin-orbit-parity coupling. Our findings underscore the crucial role of sample thickness in accessing topological states in 2D topological superconductors, offering pivotal insights into future studies of topological superconductivity.