Non-s wave superconductivity in boron-doped nanodiamond films with 0-{\pi} Josephson junction array

TL;DR

This study investigates the unconventional non-s wave superconductivity in boron-doped nanodiamond films, revealing unique transport phenomena and phase transitions influenced by microstructure and magnetic fields.

Contribution

It provides evidence for non-s wave superconductivity in boron-doped nanodiamond films and links microstructural features to superconducting properties.

Findings

Observation of a superconducting transition with non-s wave order parameter.

Detection of Berezinskii-Kosterlitz-Thouless phase transition features.

Identification of zero bias conductance peak due to Andreev bound states.

Abstract

Superconducting transport properties of granular materials are greatly influenced by the microstructure. We show that in heavily boron-doped diamond films (HBDDF) films some sharp transport features can be manipulated by applying a magnetic field and controlled finite bias current. We demonstrate the conductivity cross-over from dirty metal to the superconducting state through an insulating peak arising at a very low current or magnetic field region and particularly pronounced negative magnetoresistance with periodic oscillatory features. The current-voltage characteristics show features of the Berezinskii-Kosterlitz-Thouless (BKT) phase transitions which verifies the two-dimensional structure in HBDDF observed recently. A zero bias conductance peak can be attributed to the Andreev bound state formed at the grain boundaries of diamond nanocrystals. The set of observations can be qualitatively explained consistently through the concept of a superconducting transition with a non-s wave order parameter in the diamond heterostructures.