Magnetic-field-dependent photodynamics of single NV defects in diamond: Application to qualitative all-optical magnetic imaging

摘要

Magnetometry and magnetic imaging with nitrogen-vacancy (NV) defects indiamond rely on the optical detection of electron spin resonance (ESR).However, this technique is inherently limited to magnetic fields that are weakenough to avoid electron spin mixing. Here we focus on the high off-axismagnetic field regime for which spin mixing alters the NV defect spin dynamics.We first study in a quantitative manner the dependence of the NV defect opticalproperties on the magnetic field vector B. Magnetic-field-dependenttime-resolved photoluminescence (PL) measurements are compared to a seven-levelmodel of the NV defect that accounts for field-induced spin mixing. The modelreproduces the decreases in (i) ESR contrast, (ii) PL intensity and (iii)excited level lifetime with an increasing off-axis magnetic field. We nextdemonstrate that those effects can be used to perform all-optical magneticimaging in the high off-axis magnetic field regime. Using a scanning NV defectmicroscope, we map the stray field of a magnetic hard disk through both PL andfluorescence lifetime imaging. This all-optical method for high magnetic fieldimaging at the nanoscale might be of interest in the field of nanomagnetism,where samples producing fields in excess of several tens of milliteslas aretypical.