Temperature Dependence of the Nitrogen-Vacancy Magnetic Resonance in Diamond

The temperature dependence of the magnetic-resonance spectra of nitrogen-vacancy (NV(-)) ensembles in the range of 280-330 K was studied. Four samples prepared under different conditions were analyzed with NV(-) concentrations ranging from 10 ppb to 15 ppm. For all samples, the axial zero-field splitting (ZFS) parameter D was found to vary significantly with temperature, T, as dD/dT = -74.2(7) kHz/K. The transverse ZFS parameter E was nonzero (between 4 and 11 MHz) in all samples, and exhibited a temperature dependence of dE/(EdT) = -1.4(3) x 10(-4) K(-1). The results might be accounted for by considering local thermal expansion. The temperature dependence of the ZFS parameters presents a significant challenge for diamond magnetometers and may ultimately limit their bandwidth and sensitivity.