Squeezed Abrikosov-Josephson Vortex in Atomic-Layer Pb Superconductors Formed on Vicinal Si(111) Substrates.

Unlike bulk counterparts, two-dimensional (2D) superconductors are sensitive to disorder. Here, we investigated superconductivity of Pb atomic layers formed on vicinal substrates to reveal how surface steps with an interval shorter than the coherence length ξ affect it. Electrical transport showed reduced critical temperature and enhanced critical magnetic field. Scanning tunneling microscopy exhibited vortices elongated along the steps, that is, Abrikosov-Josephson vortices squeezed normal to the steps due to the reduced ξ. These results demonstrate that steps work as disorder and vicinal substrates provide a unique platform to manipulate the degree of disorder on 2D superconductors.

[1]  D. S. Baranov,et al.  Gold Atoms Promote Macroscopic Superconductivity in an Atomic Monolayer of Pb on Si(111). , 2022, Nano letters.

[2]  R. Arita,et al.  Gate-controlled BCS-BEC crossover in a two-dimensional superconductor , 2020, Science.

[3]  M. Mildner,et al.  Re-epithelialization and immune cell behaviour in an ex vivo human skin model , 2020, Scientific Reports.

[4]  Deung-Jang Choi,et al.  Visualization of multifractal superconductivity in a two-dimensional transition metal dichalcogenide in the weak-disorder regime. , 2018, Nano letters.

[5]  K. T. Law,et al.  Disorder-induced multifractal superconductivity in monolayer niobium dichalcogenides , 2019, Nature Physics.

[6]  E. Bauer,et al.  Visualizing heavy fermion confinement and Pauli-limited superconductivity in layered CeCoIn5 , 2018, Nature Communications.

[7]  Teresa J. Feo,et al.  Structural absorption by barbule microstructures of super black bird of paradise feathers , 2018, Nature Communications.

[8]  K. Horiba,et al.  Observation of Dirac-like energy band and ring-torus Fermi surface associated with the nodal line in topological insulator CaAgAs , 2017, 1708.06874.

[9]  A. Saranin,et al.  Superconductivity in thallium double atomic layer and transition into an insulating phase intermediated by a quantum metal state , 2017 .

[10]  T. Uchihashi.  Two-dimensional superconductors with atomic-scale thickness , 2016, 1608.06997.

[11]  T. Cren,et al.  Review of 2D superconductivity: the ultimate case of epitaxial monolayers , 2016 .

[12]  P. Kim,et al.  Nature of the quantum metal in a two-dimensional crystalline superconductor , 2015, Nature Physics.

[13]  Yasuharu Nakamura,et al.  Superconductivity protected by spin–valley locking in ion-gated MoS2 , 2015, Nature Physics.

[14]  Y. Iwasa,et al.  Metallic ground state in an ion-gated two-dimensional superconductor , 2015, Science.

[15]  L. Ioffe,et al.  Remarkable effects of disorder on superconductivity of single atomic layers of lead on silicon , 2014, Nature Physics.

[16]  L. Ioffe,et al.  Localization of preformed Cooper pairs in disordered superconductors , 2010, 1012.3630.

[17]  Xi Chen,et al.  Superconductivity in one-atomic-layer metal films grown on Si(111) , 2010 .

[18]  R. Ulbrich,et al.  Electronic transport on the nanoscale: ballistic transmission and Ohm's law. , 2009, Nano letters (Print).

[19]  M. Yakes,et al.  The dense α-√3 × √3Pb/Si(1 1 1) phase: A comprehensive STM and SPA-LEED study of ordering, phase transitions and interactions , 2006 .

[20]  A. Goldman,et al.  Superconductor‐Insulator Transitions in the Two‐Dimensional Limit , 1998 .

[21]  H. C. Montgomery.  Method for Measuring Electrical Resistivity of Anisotropic Materials , 1971 .

[22]  B. Logan,et al.  Series for Computing Current Flow in a Rectangular Block , 1971 .

[23]  A. Larkin,et al.  The influence of fluctuation pairing of electrons on the conductivity of normal metal , 1968 .