Nano-scale Inhomogeneous Superconductivity in Fe(Te1-xSex) Probed by Nanostructure-transport

TL;DR

This study provides direct nanoscale transport evidence of inhomogeneous superconductivity in Fe(Te1-xSex), showing how superconducting properties evolve with thickness and highlighting the impact of nanoscale inhomogeneity on superconductivity.

Contribution

It demonstrates the first direct nanoscale transport measurement revealing inhomogeneous superconductivity in Fe(Te1-xSex) using exfoliation and thinning techniques.

Findings

Superconducting transition varies systematically with flake thickness.

Superconductivity is suppressed in flakes thinner than 12nm.

Evidence of nanoscale inhomogeneity in superconductivity in Fe(Te1-xSex).

Abstract

Among iron based superconductors, the layered iron chalcogenide Fe(Te1-xSex) is structurally the simplest and has attracted considerable attentions. It has been speculated from bulk studies that nanoscale inhomogeneous superconductivity may inherently exist in this system. However, this has not been directly observed from nanoscale transport measurements. In this work, through simple micromechanical exfoliation and high precision low-energy ion milling thinning, we prepared Fe(Te0.5Se0.5) nano-flake with various thickness and systematically studied the correlation between the thickness and superconducting phase transition. Our result revealed a systematic evolution of superconducting transition with thickness. When the thickness of Fe(Te0.5Se0.5) flake is reduced down to 12nm, i.e. the characteristic length of Te/Se fluctuation, the superconducting current path and the metallicity of normal state in Fe(Te0.5Se0.5) atomic sheets is suppressed. This observation provides the first direct transport evidence for the nano-scale inhomogeneous nature of superconductivity in Fe(Te1-xSex).