Resistive phase transition of the superconducting Si(111)-( 7 × 3 )-In surface

Takashi Uchihashi,Tomonobu Nakayama,Puneet Mishra

doi:10.1186/1556-276x-8-167

Takashi Uchihashi, Tomonobu Nakayama + Show 1 more

Open Access

https://doi.org/10.1186/1556-276x-8-167

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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)-()-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.

Highlights

Semiconductor surface reconstructions induced by metal adatoms constitute a class of two-dimensional (2D) materials with an immense variety [1,2]
The sheet resistances (2D resistivities) R of the samples decrease significantly between 20 and 5 K, which amounts to 5% to 15% of the residual resistivity Rn,res. Their characteristic temperature dependence suggests the importance of electron-electron scattering in electron transport phenomena, which are generally marginal for conventional metal thin films
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

Summary

Introduction

Semiconductor surface reconstructions induced by metal adatoms constitute a class of two-dimensional (2D) materials with an immense variety [1,2] They are considered one form of atomic layer materials which can possess novel electronic properties and device applications [3,4]. Superconductivity was measured by scanning tunneling microscopy (STM) for atomically thin Pb films [5,6] and√three √kinds of Si(11√1) surf√ace reconstructions: SIC-Pb, ( 7 × 3)-Pb, and ( 7 × 3)-In [7]. This discovery was followed by a demonstration√of ma√croscopic superconducting currents on Si(111)-( 7 × 3)-In by direct electron transport measurements [8]. The space inversion symmetry breaking due to the presence of surface naturally leads to the Rashba spin splitting [9,10] and may help realize exotic superconductors [11]

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