Optical spin defect pairs in cubic boron nitride

TL;DR

This study demonstrates the presence of optically detected magnetic resonance in cubic boron nitride, supporting the charge transfer spin pair model and broadening the material scope for quantum sensing applications.

Contribution

It provides evidence of ODMR in cubic boron nitride, confirming the charge transfer mechanism in a new crystal phase and expanding potential quantum technology materials.

Findings

ODMR signatures observed in cubic boron nitride.

Single sub-micron cBN particle shows ODMR, indicating potential for sensing.

Charge transfer mechanism likely supports ODMR in cBN.

Abstract

Room-temperature optically active solid-state spin defects are widely known to be useful in quantum sensing applications, however, only a select range of materials have been found to host such systems. Recent measurements in the van der Waals material hexagonal boron nitride (hBN) have shown optically detected magnetic resonance (ODMR) with spin-1/2-like signatures can be explained by a charge transfer mechanism where charges move between adjacent defects forming weakly coupled spin pairs. Interestingly, these ODMR signatures have been reported in a variety of materials aside from hBN, suggesting the spin pair model provides a potentially material agnostic approach for enabling ODMR. Here, we test whether the charge transfer mechanism is supported in a different crystal phase, and report on ODMR signatures in cubic boron nitride (cBN), showing all the characteristic properties identified in hBN are preserved. We consider a selection of different cBN samples of varying size and observe ODMR from a single sub-micron cBN particle, paving the way towards sensing applications. This work further expands understanding of the ubiquity of optical spin defect pairs, and establishes the potential for exploring quantum technologies with a wider range of materials.