DC Self-Field Critical Current in Superconductor Dirac-Cone Material/Superconductor Junctions.

Evgueni Talantsev

doi:10.3390/nano9111554

Abstract

Recently, several research groups have reported on anomalous enhancement of the self-field critical currents, Ic(sf,T), at low temperatures in superconductor/Dirac-cone material/superconductor (S/DCM/S) junctions. Some papers attributed the enhancement to the low-energy Andreev bound states arising from winding of the electronic wave function around DCM. In this paper, Ic(sf,T) in S/DCM/S junctions have been analyzed by two approaches: modified Ambegaokar-Baratoff and ballistic Titov-Beenakker models. It is shown that the ballistic model, which is traditionally considered to be a basic model to describe Ic(sf,T) in S/DCM/S junctions, is an inadequate tool to analyze experimental data from these type of junctions, while Ambegaokar-Baratoff model, which is generally considered to be a model for Ic(sf,T) in superconductor/insulator/superconductor junctions, provides good experimental data description. Thus, there is a need to develop a new model for self-field critical currents in S/DCM/S systems.

Highlights

Intrinsic superconductors [1] of rectangular cross-section exhibit non-dissipative temperature dependent transport self-field critical current, Ic(sf,T), which is given by the following universal equation [2,3,4]: √ Ic(sf, T) = φ0 π·μ0 · ln(1+ 2·κc(T)) · λ3ab (T) λc (T) b ·tanh b λc (T)+ ln(1√+ 2·γ(T)·κc(T)) γ(T)·λ3ab (T)
Equations (4), (5), (7), and (8) will be applied to fit experimental Ic(sf,T) datasets for a variety of superconductor/Dirac-cone material/superconductor (S/DCM/S) junctions with the purpose to reveal the primary superconducting parameters of these systems and by comparison deduced parameters with weak-coupling s-wave BCS limits we show that the modified Ambegaokar and Baratoff model (Equations (4) and (5)) [51,52] describes the superconducting state in S/DCM/S junctions with higher accuracy
Device 1 has W = 6 μm, L = 1 μm, and ξs = 16 μm [63]. This means that the ballistic limit of L

Summary

Introduction

Intrinsic superconductors [1] of rectangular cross-section (with width 2a and thickness 2b) exhibit non-dissipative temperature dependent transport self-field critical current, Ic(sf,T) (i.e., when no external magnetic field applies), which is given by the following universal equation [2,3,4]: √ Ic(sf, T) = φ0 π·μ0 · ln(1+ 2·κc(T)) · λ3ab (T) λc (T) b ·tanh b λc (T)+ ln(1√+ 2·γ(T)·κc(T)) γ(T)·λ3ab (T)

Results

Discussion

Conclusion