Article

# Metallic transport in a monatomic layer of in on a silicon surface.

Department of Physics, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

Physical Review Letters (Impact Factor: 7.73). 03/2011; 106(11):116802. DOI: 10.1103/PhysRevLett.106.116802 Source: PubMed

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**ABSTRACT:**In situ micro-four-point-probe conductivity measurements in ultrahigh vacuum revealed that the Si(111)-striped incommensurate-Pb surface showed the superconductivity transition at 1.1 K. Both of the hexagonal and rectangular phases of Si(111)7×3-In surface showed superconductivity at 2.4 and 2.8 K, respectively. By applying magnetic field perpendicular to the surface, the upper critical field was deduced to be 0.1–1 T. The derived Ginzburg-Landau coherence length of the Cooper pairs was several tens of nm, which was much smaller than the Pippard’s coherence length estimated from the band structures. The short coherence length is determined by the carrier mean free path.Physical Review Letters 06/2013; · 7.73 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**Recently, superconductivity was found on semiconductor surface reconstructions induced by metal adatoms, promising a new field of research where superconductors can be studied from the atomic level.Here we measure the electron transport properties of the Si(111)-(¿7 × ¿3)-In surface near the resistive phase transition and analyze the data in terms of theories of two-dimensional (2D) superconductors.In the normal state, the sheet resistances (2D resistivities) R¿ of the samples decrease significantly between 20 and 5 K, suggesting the importance of the electron-electron scattering in electron transport phenomena.The decrease in R¿ is progressively accelerated just above the transition temperature (Tc) due to the direct (Aslamazov-Larkin term) and the indirect (Maki-Thompson term) superconducting fluctuation effects.A minute but finite resistance tail is found below Tc down to the lowest temperature of 1.8 K, which may be ascribed to a dissipation due to free vortex flow.The present study lays the ground for a future research aiming to find new superconductors in this class of materials.Nanoscale Research Letters 04/2013; 8(1):167. · 2.52 Impact Factor -
##### Article: Mechanical Properties of Various Phases on In/Si(111) Surfaces Revealed by Atomic Force Microscopy

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**ABSTRACT:**In/Si(111) surfaces have a variety of phases, among which 4× 1 and \sqrt{7}×\sqrt{3} show intriguing one-/two-dimensional (1D/2D) electronic properties. Here, we carry out extensive experiments to investigate the mechanical properties of various phases on the surfaces by atomic force microscopy at room temperature. Energy dissipation associated with flexibility is measured at the atomic scale. In the 4× 1 phase, dissipation locally increases at the inner parts of couples of In chains, which correspond to mobile In atoms in a dynamical fluctuation model for the phase transition. An extremely large dissipation signal is obtained on the \sqrt{7}×\sqrt{3} phase, indicating that a single atomic layer of In is weakly attached to the Si substrate, which is consistent with the 2D electronic properties.Applied Physics Express 05/2013; 6(5):5201-. · 2.73 Impact Factor

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