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Published online: 20 January 2010 | doi:10.1038/nchina.2010.8

Nanotechnology: Superconductivity goes atom-thin

Felix Cheung

Introduction

© (2010) Nature Physics

Previous studies have demonstrated superconductivity in ultrathin metal films down to the thickness of a few atomic layers. However, it has been unclear whether a single layer of ordered metal atoms — a thin film at its extreme — can be superconducting. Qikun Xue and Xi Chen at Tsinghua University in Beijing and co-workers¹ have now unambiguously demonstrated superconductivity in a single layer of lead (and indium) atoms.

The researchers grew their layers of lead or indium with atomic precision on a silicon substrate using molecular beam epitaxy. The 'atom-thin' lead film forms one of two structural phases under these conditions: the striped incommensurate (SIC) phase (pictured top) and the '√7×√3' phase. The indium film forms only the √7×√3 phase.

Scanning tunnelling microscopy measurements showed that monoatomic SIC lead, √7×√3 lead and √7×√3 indium films are superconducting at temperatures of 1.83 K, 1.52 K and 3.18 K, respectively. By the same measurements, the researchers observed the presence of superconducting vortices (pictured bottom) in the SIC lead film under a magnetic field.

Angle-resolved photoemission spectroscopy measurements revealed that the superconductivity is due to the interplay between metallic lead–lead (indium–indium) and covalent lead–silicon (indium–silicon) bondings.

The authors of this work are from:
Key Lab for Atomic and Molecular Nanoscience, Department of Physics, Tsinghua University, Beijing, China; Institute of Physics, Chinese Academy of Sciences, Beijing, China; Department of Physics and Material Research Institute, Pennsylvania State University, Pennsylvania, USA; Department of Physics, Chinese University of Hong Kong, Hong Kong, China.

Reference

1. Zhang, T. et al. Superconductivity in one-atomic-layer metal films grown on Si(111). Nature Phys. doi:10.1038/nphys1499 (2010). | Article | OpenURL