A combined method for synthesis of superconducting Cu doped Bi2Se3

TL;DR

This paper introduces a two-step synthesis method for superconducting Cu-doped Bi2Se3, demonstrating that pre-doped Cu facilitates superconductivity and providing insights into Cu dopant locations.

Contribution

A novel combined synthesis approach using melt-growth and electrochemical methods to produce superconducting Cu-doped Bi2Se3 with improved properties.

Findings

Pre-doped Cu enhances superconducting performance.

Samples from Cu0.15Bi2Se3 show reliable zero-resistance.

Optimal quenching improves superconducting shielding fraction.

Abstract

We present a two-step technique for the synthesis of superconducting CuxBi2Se3. Cu0.15Bi2Se3 single crystals were synthesized using the melt-growth method. Although these samples are non-superconducting, they can be employed to generate high quality superconducting samples if used as precursors in the following electrochemical synthesis step. Samples made from Cu0.15Bi2Se3 reliably exhibit zero-resistance even under the non-optimal quenching condition, while samples made from pristine Bi2Se3 require fine tuning of the quenching conditions to achieve similar performance. Moreover, under the optimal quenching condition, the average superconducting shielding fraction was still lower in the samples made from pristine Bi2Se3 than in the samples made from Cu0.15Bi2Se3. These results suggest that the pre-doped Cu atoms facilitate the formation of a superconducting percolation network. We also discuss the useful clues that we gathered about the locations of Cu dopants that are responsible for superconductivity.