Fermi-arc supercurrent oscillations in Dirac semimetal Josephson junctions

Cai-Zhen Li,An-Qi Wang,Alexander Brinkman,Zhi-Min Liao,Da-Peng Yu,Wen-Zhuang Zheng,Chuan Li

doi:10.1038/s41467-020-15010-8

Abstract

One prominent hallmark of topological semimetals is the existence of unusual topological surface states known as Fermi arcs. Nevertheless, the Fermi-arc superconductivity remains elusive. Here, we report the critical current oscillations from surface Fermi arcs in Nb-Dirac semimetal Cd3As2-Nb Josephson junctions. The supercurrent from bulk states are suppressed under an in-plane magnetic field ~0.1 T, while the supercurrent from the topological surface states survives up to 0.5 T. Contrary to the minimum normal-state conductance, the Fermi-arc carried supercurrent shows a maximum critical value near the Dirac point, which is consistent with the fact that the Fermi arcs have maximum density of state at the Dirac point. Moreover, the critical current exhibits periodic oscillations with a parallel magnetic field, which is well understood by considering the in-plane orbital effect from the surface states. Our results suggest the Dirac semimetal combined with superconductivity should be promising for topological quantum devices.

Highlights

One prominent hallmark of topological semimetals is the existence of unusual topological surface states known as Fermi arcs
In the surface state dominant regime, the critical supercurrent shows a maximum value near the Dirac point, consistent with the fact that the Fermi arcs have the maximum density of states at the Dirac point
Andreev reflections in the Dirac semimetal Josephson junction

Summary

Introduction

One prominent hallmark of topological semimetals is the existence of unusual topological surface states known as Fermi arcs. Besides the transport research in its normal phase, efforts have recently been made to couple the Fermi-arc surface states to a superconductor with the expectation of Majorana fermions[18,19,20,21] Such proximitized superconductivity has been observed in Cd3As2, including surface carried Josephson supercurrent[22], π and 4π Josephson effects[23,24]. The Fermi-arc supercurrent shows periodic oscillations with in-plane parallel magnetic field, which is attributed to the in-plane field orbital interference of the surface Fermi arcs Such magnetic field and gate modulation of superconducting Fermi arcs open up a new avenue for the manipulation of Majorana fermions, which might be significant to the topological quantum computation

Methods

Results

Conclusion