Superconductivity in Cu Co-Doped SrxBi2Se3 Single Crystals.

Aleksandr Yu Kuntsevich,Evgenii G Chigevskii,George V Rybalchenko,Yuri G Selivanov,Oleg A Sobolevskiy,Victor P Martovitskii,Mikhail I Bannikov

doi:10.3390/ma12233899

Abstract

In this study, we grew Cu co-doped single crystals of a topological superconductor candidate SrBiSe, and studied their structural and transport properties. We reveal that the addition of even as small an amount of Cu co-dopant as 0.6 atomic %, completely suppresses superconductivity in SrBiSe. Critical temperature (∼2.7 K) is rather robust with respect to co-doping. We show that Cu systematically increases the electron density and lattice parameters a and c. Our results demonstrate that superconductivity in SrBiSe-based materials is induced by significantly lower Sr doping level than commonly accepted , and it strongly depends on the specific arrangement of Sr atoms in the host matrix. The critical temperature in superconductive Sr-doped BiSe is shown to be insensitive to carrier density.

Highlights

The emergence of unusual superconductivity (SC) in novel topological quantum materials is one of the hottest topics in condensed matter physics and material science
Its superconductive relative Srx Bi2 Se3, discovered in 2015 [16,17,18], had much better structural quality, demonstrated stability of superconductivity during the storage at ambient conditions, and showed a superconductive volume fraction up to 100% [16,19]. This structural supremacy allowed the discovery of new physics: in particular, resistive nematicity [20,21,22], the Dirac-like character of surface superconducting states [23] and nematic effects above critical temperature [24,25]
We show that the latter fact is in line with the present understanding of the unusual superconductivity in this material

Summary

Introduction

The emergence of unusual superconductivity (SC) in novel topological quantum materials is one of the hottest topics in condensed matter physics and material science. Its superconductive relative Srx Bi2 Se3 , discovered in 2015 [16,17,18], had much better structural quality, demonstrated stability of superconductivity during the storage at ambient conditions, and showed a superconductive volume fraction up to 100% [16,19]. This structural supremacy allowed the discovery of new physics: in particular, resistive nematicity [20,21,22], the Dirac-like character of surface superconducting states [23] and nematic effects above critical temperature [24,25].

Methods

Discussion

Conclusion