Phase Slips and Metastability in Granular Boron-doped Nanocrystalline Diamond Microbridges

TL;DR

This study investigates phase slips and metastability in boron-doped nanocrystalline diamond microbridges, revealing intrinsic Josephson junction behavior and controllable switching between superconducting states due to their microstructure.

Contribution

It provides evidence of phase slippage in 3D BNCD microbridges caused by its microstructure, introducing a new understanding of metastability and switching in these materials.

Findings

Evidence of phase slippage in BNCD microbridges.

Intrinsic Josephson junction array behavior due to microstructure.

Deterministic switching between superconducting states.

Abstract

A phase slip is a localized disturbance in the coherence of a superconductor allowing an abrupt 2$\pi$ phase shift. Phase slips are a ubiquitous feature of one-dimensional superconductors and also have an analogue in two-dimensions. Here we present electrical transport measurements on boron-doped nanocrystalline diamond (BNCD) microbridges where, despite their three-dimensional macroscopic geometry, we find clear evidence of phase slippage in both the resistance-temperature and voltage-current characteristics. We attribute this behavior to the unusual microstructure of BNCD. We argue that the columnar crystal structure of BNCD forms an intrinsic Josephson junction array that supports a line of phase slippage across the microbridge. The voltage-state in these bridges is metastable and we demonstrate the ability to switch deterministically between different superconducting states by applying electromagnetic noise pulses. This metastability is remarkably similar to that observed in $\delta$-MoN nanowires, but with a vastly greater response voltage.