Wide-band nanoscale magnetic resonance spectroscopy using quantum relaxation of a single spin in diamond

Abstract

We demonstrate a wide-band all-optical method of nanoscale magnetic resonance (MR) spectroscopy under ambient conditions. Our method relies on cross-relaxation between a probe spin, the electronic spin of a nitrogen-vacancy centre in diamond, and target spins as the two systems are tuned into resonance. By optically monitoring the spin relaxation time (T1) of the probe spin while varying the amplitude of an applied static magnetic field, a frequency spectrum of the target spin resonances, a T1-MR spectrum, is obtained. As a proof of concept, we measure T1-MR spectra of a small ensemble of 14 N impurities surrounding the probe spin within the diamond, with each impurity comprising an electron spin 1/2 and a nuclear spin 1. The intrinsically large bandwidth of the technique and probe properties allows us to detect both electron spin transitions -in the GHz range -and nuclear spin transitions -in the MHz range -of the 14 N spin targets. The measured frequencies are found to be in excellent agreement with theoretical expectations, and allow us to infer the hyperfine, quadrupole and gyromagnetic constants of the target spins. Analysis of the strength of the resonances obtained in the T1-MR spectrum reveals that the electron spin transitions are probed via dipole interactions, while the nuclear spin resonances are dramatically enhanced by hyperfine coupling and an electron-mediated process. Finally, we investigate theoretically the possibility of performing T1-MR spectroscopy on nuclear spins without hyperfine interaction and predict single-proton sensitivity using current technology. This work establishes T1-MR as a simple yet powerful technique for nanoscale MR spectroscopy, with broadband capability and a projected sensitivity down to the single nuclear spin level.

Microwave-free nuclear magnetic resonance at molecular scales

“…This technique was proposed and demonstrated for quantitative electron spin resonance spectroscopy using an ensemble of NV centres25 and extended to hyperfine-coupled nuclear spin spectroscopy with single NV centres35. The ultimate goal of nano-NMR is the spectroscopic detection of bare nuclear spins in molecular systems (Fig.…”

Level anti-crossing magnetometry with color centers in diamond

“…[13]. The presented traces contain several features extensively discussed in past [17][18][19] and more recent [13,20,21] works. In particular, the initial gradual decrease in the observed signals is associated either with a reduction in PL emission (samples W4, C7, F11; Fig.…”

Eddy-Current Imaging with Nitrogen-Vacancy Centers in Diamond

“…The magneto-metric scheme we followed for this measurements enables all-optical detection of AC fields. [12][13][14][15][16][17] . We investigated three different areas: α) the slope from 0 to ∼ 25 mT, β) the cross-relaxation features around 50 mT and γ) the ground-state level anticrossing (GSLAC) feature at 102.4 mT.…”