Atomic-layer Rashba-type superconductor protected by dynamic spin-momentum locking

• Published in: arXiv.org
• Main Authors: Yoshizawa, Shunsuke, Kobayashi, Takahiro, Nakata, Yoshitaka, Yaji, Koichiro, Yokota, Kenta, Komori, Fumio, Shin, Shik, Sakamoto, Kazuyuki, Uchihashi, Takashi
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 12.03.2021
• Subjects: Cooper pairs; Elastic scattering; Electron transport; Fermi surfaces; Locking; Magnetic fields; Momentum; Physics - Mesoscale and Nanoscale Physics; Physics - Superconductivity; Spin dynamics; Spin-orbit interactions; Superconductivity; Superconductors
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2103.07143

Spin-momentum locking is essential to the spin-split Fermi surfaces of inversion-symmetry broken materials, which are caused by either Rashba-type or Zeeman-type spin-orbit coupling (SOC). While the effect of Zeeman-type SOC on superconductivity has experimentally been shown recently, that of Rashba-type SOC remains elusive. Here we report on convincing evidence for the critical role of the spin-momentum locking on crystalline atomic-layer superconductors on surfaces, for which the presence of the Rashba-type SOC is demonstrated. In-situ electron transport measurements reveal that in-plane upper critical magnetic field is anomalously enhanced, reaching approximately three times the Pauli limit at \(T = 0\). Our quantitative analysis clarifies that dynamic spin-momentum locking, a mechanism where spin is forced to flip at every elastic electron scattering, suppresses the Cooper pair-breaking parameter by orders of magnitude and thereby protects superconductivity. The present result provides a new insight into how superconductivity can survive the detrimental effects of strong magnetic fields and exchange interactions.