Influence of 14N hyperfine interaction on electron nuclear double resonance of boron vacancy in hexagonal boron nitride

TL;DR

This paper investigates the hyperfine interactions affecting ENDOR spectra of nitrogen near boron vacancies in hexagonal boron nitride, combining theoretical calculations with experimental data to explain spectral shifts.

Contribution

It provides a detailed theoretical analysis of hyperfine interactions in hBN defects, matching experimental ENDOR spectra with second-order perturbation calculations.

Findings

Hyperfine interaction causes measurable shifts in ENDOR spectra.

Perturbation theory accurately predicts spectral line positions.

Nuclear state admixture is approximately 0.04-0.07%.

Abstract

The research focuses on the explanation of a phenomenon observed in the spectra of electron nuclear resonance (ENDOR) pertaining to nitrogen atoms adjacent to the boron vacancy (VB) defect in hexagonal boron nitride (hBN). The phenomenon is manifested as a shift of the ENDOR spectrum lines with respect to the nitrogen Larmor frequency. It is hypothesized that these shifts are indicative of a substantial hyperfine interaction between the VB defect and the 14N nuclei in hBN. A calculation utilizing second-order perturbation theory was executed to determine the positions of the ENDOR spectrum lines, resulting in the formulation of correction equations. The values obtained from the perturbation theory corrections align well with the experimental results. The extent of nuclear state admixture into electron states was found to be around 0.04-0.07%.