Scanning Nanospin Ensemble Microscope for Nanoscale Magnetic and Thermal Imaging

Abstract

Quantum sensors based on solid-state spins provide tremendous opportunities in a wide range of fields from basic physics and chemistry to biomedical imaging. However, integrating them into a scanning probe microscope to enable practical, nanoscale quantum imaging is a highly challenging task. Recently, the use of single spins in diamond in conjunction with atomic force microscopy techniques has allowed significant progress towards this goal, but generalisation of this approach has so far been impeded by long acquisition times or by the absence of simultaneous topographic information. Here we report on a scanning quantum probe microscope which solves both issues, by employing a nano-spin ensemble hosted in a nanodiamond. This approach provides up to an order of magnitude gain in acquisition time, whilst preserving sub-100 nm spatial resolution both for the quantum sensor and topographic images. We demonstrate two applications of this microscope. We first image nanoscale clusters of maghemite particles through both spin resonance spectroscopy and spin relaxometry, under ambient conditions. Our images reveal fast magnetic field fluctuations in addition to a static component, indicating the presence of both superparamagnetic and ferromagnetic particles. We next demonstrate a new imaging modality where the nano-spin ensemble is used as a thermometer. We use this technique to map the photo-induced heating generated by laser irradiation of a single gold nanoparticle in a fluid environment. This work paves the way towards new applications of quantum probe microscopy such as thermal/magnetic imaging of operating microelectronic devices and magnetic detection of ion channels in cell membranes.In recent years, quantum sensing has attracted increasing attention because it opens up the possibilities for non-invasive sensing with nanoscale mapping potential and single atom sensitivity. The model system for these studies has been the negatively charged nitrogen-vacancy (NV) centre in diamond, which has shown great promise as an atomic-sized sensor operating under ambient conditions [1][2][3]. The NV centre is a photostable point defect whose electronic ground state is a spin triplet that can be initialised and read out by optical means [4,5]. This makes it possible to detect the spin resonance of a single NV centre and coherently control its spin state. Owing to interaction with the local environment, measurement of the spectral and temporal properties of an NV centre's spin provides access to a number of local properties, such as the magnetic field, electric field, pressure or temperature [6][7][8][9][10]. Furthermore, NV sensors are capable not only of measuring static fields but also fluctuating ones. This, in turn, allows retrieval of spectral information from a sample [11][12][13][14][15][16]. This capability was recently used to perform nuclear magnetic resonance spectroscopy on a small ensemble of protons [17,18].In order to obtain spatial information about the sample's properties, the NV probe must be scanned relative ...

Not All Fluorescent Nanodiamonds Are Created Equal: A Comparative Study

“…The T 1 time was determined by fitting a stretched exponential function to each relaxation curve (see Figure C). A stretched exponential function was used to fit the T 1 relaxation curves from the NV ensembles, given there is a distribution of T 1 times from the individual NV − centers within a nanodiamond …”

“…A stretched exponential function was used to fit the T 1 relaxation curves from the NV ensembles, given there is a distribution of T 1 times from the individual NV − centers within a nanodiamond. [13,38,39] SEM images of each particle were analyzed using ImageJ [40] to determine the 2D area A covered by the particle, the major and minor axes of an ellipse fitted to this 2D area, and the particle circularity. The particle's aspect ratio was calculated as the ratio of the major and minor axis of the fitted ellipse.…”

Measuring Nanoscale Thermostability of Cell Membranes with Single Gold–Diamond Nanohybrids

“…[15,16] At room temperature,t he magnitude of the thermal shift is 0.015 nm 8 8C À1 . [16][17][18] Compared with the temperature sensing based on optically detected magnetic resonance, [8][9][10][11][12] this alloptical method has the advantages of being simple,s traightforward, and readily implementable in any confocal microscope equipped with aC CD-based monochromator for practical biological applications.F igure 1b displays at ypical fluorescence spectrum obtained for as ingle 100-nm FND particle spin-coated on ag lass coverslip at 25 8 8C. TheZ PL center (l 0 )can be extracted by fitting the spectrum over 610-660 nm to aL orentzian function, along with an exponential function to correct the baseline.…”

Advances in diamond nanofabrication for ultrasensitive devices

“…The use of the AFM tip for magnetic scanning with single NVcenters usually brings about issues with the unavailability of simultaneous topographic scanning and the lengthening of the acquisition time. These were recently tackled by employing a nanospin ensemble of 100 NV-centers hosted in a nano-diamond (Figure 10), providing up to an order of magnitude gain in the signal-to-noise ratio (and thus acquisition time) with respect to a single NV-center, while preserving sub-100 nm spatial resolution 88 . When integrated with nanomechanical systems, NV-centers show strong spin-phonon coupling in nanoscale dimension resonators [89][90][91] mediated by the lattice strain effect as shown by incorporating photo-stable NV-centers in diamond cantilevers at different location from the cantilever base 90 .…”