paper

Spin Coherence and N ESEEM Effects of Nitrogen-Vacancy Centers in Diamond with X-band Pulsed ESR

arXiv:1603.04035 · doi:10.1016/j.diamond.2016.12.009

Abstract

Pulsed ESR experiments are reported for ensembles of negatively-charged nitrogen-vacancy centers (NV) in diamonds at X-band magnetic fields (280-400 mT) and low temperatures (2-70 K). The NV centers in synthetic type IIb diamonds (nitrogen impurity concentration ~ppm) are prepared with bulk concentrations of cm to cm by high-energy electron irradiation and subsequent annealing. We find that a proper post-radiation anneal (1000C for 60 mins) is critically important to repair the radiation damage and to recover long electron spin coherence times for NVs. After the annealing, spin coherence times of T~ms at 5~K are achieved, being only limited by C nuclear spectral diffusion in natural abundance diamonds. At X-band magnetic fields, strong electron spin echo envelope modulation (ESEEM) is observed originating from the central N nucleus. The ESEEM spectral analysis allows for accurate determination of the N nuclear hypefine and quadrupole tensors. In addition, the ESEEM effects from two proximal C sites (second-nearest neighbor and fourth-nearest neighbor) are resolved and the respective C hyperfine coupling constants are extracted.

10 pages, 5 figures

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