Zero field line in the magnetic spectra of negatively charged nitrogen-vacancy centers in diamond

TL;DR

This study identifies a unique zero-field line in the magnetic spectra of negatively charged nitrogen-vacancy centers in diamond, revealing its properties and proposing a dipole-dipole interaction model as its mechanism.

Contribution

The paper reports the discovery of a new zero-field line in NV- centers and introduces a model based on dipole-dipole interactions to explain its origin.

Findings

A narrow zero-field line in magnetic spectra of NV- centers

Line's weak dependence on sample orientation and polarization

Non-linear relation between line magnitude and excitation light intensity

Abstract

The dependence of the luminescence of diamonds with negatively charged nitrogen-vacancy centers (NV-) vs. applied magnetic field (magnetic spectrum) was studied. A narrow line in zero magnetic field was discovered. The properties of this line are considerably different from those of other narrow magnetic spectrum lines. Its magnitude is weakly dependent of the orientation of the single-crystal sample to the external magnetic field. This line is also observed in a powdered sample. The shape of the line changes greatly when excitation light polarization is varied. The magnitude of the line has a non-linear relation to excitation light intensity. For low intensities this dependence is close to a square law. To explain the mechanism giving rise to this line in the magnetic spectrum, we suggest a model based on the dipole-dipole interaction between different NV- centers.