Crossover from Conventional to Unconventional Superconductivity in 2M-WS2

Piumi Samarawickrama; Joseph McBride; Sabin Gautam; ZhuangEn Fu; Kenji Watanabe; Takashi Taniguchi; Wenyong Wang; Jinke Tang; John Ackerman; Brian M. Leonard; Jifa Tian

doi:10.1021/acs.nanolett.4c05257

arXiv · 2412.06612

Crossover from Conventional to Unconventional Superconductivity in 2M-WS2

Piumi Samarawickrama·Joseph McBride·Sabin Gautam·ZhuangEn Fu·Kenji Watanabe·Takashi Taniguchi·Wenyong Wang·Jinke Tang·John Ackerman·Brian M. Leonard·Jifa Tian

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Abstract

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.

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Piumi Samarawickrama, Joseph McBride, Sabin Gautam, ZhuangEn Fu, Kenji Watanabe, Takashi Taniguchi, Wenyong Wang, Jinke Tang, John Ackerman, Brian M. Leonard, Jifa Tian. 2024-12-09. Crossover from Conventional to Unconventional Superconductivity in 2M-WS2. https://doi.org/10.1021/acs.nanolett.4c05257

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