87 research outputs found
Generation of spin-polarized currents via cross-relaxation with dynamically pumped paramagnetic impurities
Key to future spintronics and spin-based information processing technologies
is the generation, manipulation, and detection of spin polarization in a solid
state platform. Here, we theoretically explore an alternative route to spin
injection via the use of dynamically polarized nitrogen-vacancy (NV) centers in
diamond. We focus on the geometry where carriers and NV centers are confined to
proximate, parallel layers and use a 'trap-and-release' model to calculate the
spin cross-relaxation probabilities between the charge carriers and neighboring
NV centers. We identify near-unity regimes of carrier polarization depending on
the NV spin state, applied magnetic field, and carrier g-factor. In particular,
we find that unlike holes, electron spins are distinctively robust against
spin-lattice relaxation by other, unpolarized paramagnetic centers. Further,
the polarization process is only weakly dependent on the carrier hopping
dynamics, which makes this approach potentially applicable over a broad range
of temperatures.C.A.M. acknowledges support from the National
Science Foundation through Grant No. NSF-1314205.
M.W.D. acknowledges support from the Australian Research
Council through Grant No. DP120102232
Spin readout via spin-to-charge conversion in bulk diamond nitrogen-vacancy ensembles
We demonstrate optical readout of ensembles of nitrogen-vacancy(NV) center
spins in a bulk diamond sample via spin-to-charge conversion. A high power 594
nm laser is utilized to selectively ionize these paramagnetic defects in the
spin state with a contrast of up to 12%. In comparison with the conventional
520 nm spin readout, spin-to-charge-conversion-based readout provides higher
signal-to-noise ratio, with tenfold sensing measurement speedup for millisecond
long pulse sequences. This level of performance was achieved for an NV-
ionization of only 25%, limited by the ionization and readout laser powers.
These observations pave the way to a range of high-sensitivity metrology
applications where the use of NV- ensembles in bulk diamond has proven useful,
including sensing and imaging of target materials overlaid on the diamond
surface
Magnetometry of random AC magnetic fields using a single Nitrogen-Vacancy center
We report on the use of a single NV center to probe fluctuating AC magnetic
fields. Using engineered currents to induce random changes in the field
amplitude and phase, we show that stochastic fluctuations reduce the NV center
sensitivity and, in general, make the NV response field-dependent. We also
introduce two modalities to determine the field spectral composition, unknown a
priori in a practical application. One strategy capitalizes on the generation
of AC-field-induced coherence 'revivals', while the other approach uses the
time-tagged fluorescence intensity record from successive NV observations to
reconstruct the AC field spectral density. These studies are relevant for
magnetic sensing in scenarios where the field of interest has a non-trivial,
stochastic behavior, such as sensing unpolarized nuclear spin ensembles at low
static magnetic fields.Comment: 11 pages, 3 figure
The diamond Nitrogen-Vacancy center as a probe of random fluctuations in a nuclear spin ensemble
New schemes that exploit the unique properties of Nitrogen-Vacancy (NV)
centers in diamond are presently being explored as a platform for
high-resolution magnetic sensing. Here we focus on the ability of a NV center
to monitor an adjacent mesoscopic nuclear spin bath. For this purpose, we
conduct comparative experiments where the NV spin evolves under the influence
of surrounding 13C nuclei or, alternatively, in the presence of asynchronous AC
fields engineered to emulate bath fluctuations. Our study reveals substantial
differences that underscore the limitations of the semi-classical picture when
interpreting and predicting the outcome of experiments designed to probe small
nuclear spin ensembles. In particular, our study elucidates the NV center
response to bath fluctuations under common pulse sequences, and explores a
detection protocol designed to probe time correlations of the nuclear spin bath
dynamics. Further, we show that the presence of macroscopic nuclear spin order
is key to the emergence of semi-classical spin magnetometry.Comment: 30 pages, 4 figure
METHOD FOR HYPER-POLARIZING NUCLEAR SPNS AT ARBTRARY MAGNETIC FELDS
A method of dynamically polarizing the nuclear spin host of nitrogen-vacancy (NV) centers in diamond is provided. The method uses optical, microwave and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Nitrogen nuclear spin initialization approaching 80% at room temperature is demonstrated both in ensemble and single NV centers without relying on level anti-crossings. This makes the method applicable at arbitrary magnetic fields
Long-term data storage in diamond
The negatively charged nitrogen vacancy (NV−) center in diamond is the focus of widespread attention for applications ranging from quantum information processing to nanoscale metrology. Althoughmostwork so far has focused on the NV− optical and spin properties, control of the charge state promises complementary opportunities. One intriguing possibility is the long-term storage of information, a notion we hereby introduce using NV-rich, type 1b diamond. As a proof of principle, we use multicolor optical microscopy to read, write, and reset arbitrary data sets with twodimensional (2D) binary bit density comparable to present digital-video-disk (DVD) technology. Leveraging on the singular dynamics of NV− ionization, we encode information on different planes of the diamond crystal with no crosstalk, hence extending the storage capacity to three dimensions. Furthermore, we correlate the center’s charge state and the nuclear spin polarization of the nitrogen host and showthat the latter is robust to a cycle of NV− ionization and recharge. In combination with super-resolution microscopy techniques, these observations provide a route toward subdiffraction NV charge control, a regime where the storage capacity could exceed present technologies
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