Magnetic Resonance Force Microscopy Research Articles

Bridged resonator based on assembled Si thin wire

In this research, the Si thin wire has been assembled on a glass trench to be a bridged resonator, which has the potential to measure multi-dimensional force by the combination of strain sensing and field effect transistor (FET) sensing using the mechanical vibration. The Si thin wire was designed to be the suitable structure to improve the detectable minimum force and measurement time. Analysing the current spectrum flowing in the resonator, the vibration measurement using the strain sensing and FET sensing, was demonstrated in a single dimension. The resonant frequency was observed by the spectrum of the current flowing in Si thin wire, which was observed at the same frequency by a laser Doppler vibrometer. Using the gate electrode, the additionally modulated current was observed. The effective and faster force mapping measurements using magnetic resonance force microscopy are expected by the proposed multi-dimensional force detection.

Fluorinated sulfonated poly (arylene ether)s bearing semi-crystalline structures for highly conducting and stable proton exchange membranes

An aromatic nucleophilic substitution reaction-based direct polycondensation of 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,4-bis(4-fluorobenzoyl)benzene (1,4-FBB), and 3,3′-disulfonate-4,4′-difluorodiphenylsulfone is used to synthesize 1,4-FBB in fluorinated sulfonated semi-crystalline poly (arylene ether) copolymers. The ion exchange capacity, mechanical stability, thermal stability, and oxidative stability of membranes with various degrees of sulfonation and water absorption are studied. 1H nuclear magnetic resonance and atomic force microscopy verify the chemical structure of the synthesized ion exchange membrane. The semi-crystalline 6 F-membrane shows reliable chemical, mechanical, thermal, and electrochemical stability. Compared to Nafion 212®, which is a commercial ion exchange membrane, the semi-crystalline 6 F-membrane shows excellent cell performance as current density is increased. All the results mentioned above indicate that this semi-crystalline 6 F-membrane is a good candidate to replace the commercial membranes.

Soft-Clamped Phononic Dimers for Mechanical Sensing and Transduction

Coupled micro- and nanomechanical resonators are of significant interest within a number of areas of research, ranging from synchronisation, nonlinear dynamics and chaos, to quantum sensing and transduction. Building upon our work on soft-clamped membrane resonators, here we present a study on phononic dimers, consisting of two defects embedded in a phononic crystal membrane. These devices exhibit widely tunable (2-100 kHz) inter-defect coupling strengths, leading to delocalized hybrid modes with mechanical Qf-products > 10^14 Hz at room temperature,ensuring low thermomechanical force noise. The mode splitting exhibits a strong dependence on the dimer orientation within the crystal lattice, as well as the spatial separation between the two defects. Given the importance of dynamic range for sensing applications, we characterize the relevant mechanical nonlinearities, specifically the self- and cross-Duffing parameters, as well as self and cross-nonlinear dampings. This work establishes soft-clamped resonators with engineered spatial and spectral multi-mode structure as a versatile mechanical platform both in the classical and quantum regimes. Applications in microwave-to-optical transduction and magnetic resonance force microscopy are particularly attractive prospects.

Cocoa shell: an industrial by-product for the preparation of suspensions of holocellulose nanofibers and fat

Cocoa shell (CS) is a by-product of the chocolate industry with limited economic benefit and a high environmental impact. In this study, a new material for the food industry that consists of nanocellulose fibers with CS fat was successfully isolated (yield of approximately 7.12%). The material was characterized with attenuated total reflection–Fourier transform infrared spectroscopy (ATR–FTIR), solid-state 13C nuclear magnetic resonance (13C NMR), X-ray diffraction (XRD), fluorescence and atomic force microscopy (AFM). The XRD, 13C NMR, and ATR–FTIR results suggest that the structure of the cellulosic CS fibers can be interpreted as cellulose Iβ. The crystallinity index (CrI) of an isolated sample was investigated by different methods with ATR–FTIR, 13C NMR, and XRD. According to the results, 13C NMR and XRD are the most adequate methods for quantifying the CrI of cellulosic samples in the presence of fat. In addition, the XRD results indicate that approximately 65 to 70% of the sample was crystalline. According to the fluorescence microscopy results, the cellulosic sample formed a suspension with fat, and the AFM results show that the cellulosic part of the sample had nanometric diameters between 30–80 nm with high aspect ratios. Consequently, a suspension of nanocellulose, hemicellulose, and fat was isolated from CS by chemical and mechanical treatments. The new material can be called a “suspension of holocellulose nanofibers and fat” owing to its composition and fiber diameters. The high aspect ratio of the nanocellulose fibers in the suspension resulted in an entangled network that stabilized the CS fat.

Измерение магнитных свойств электронов проводимости

We consider various methods and techniques for measuring electron magnetization and susceptibility, which are used in experimental condensed matter physics. The list of considered methods for macroscopic measurements includes magnetomechanic, electromagnetic, modulation-type, and also thermodynamic methods based on the chemical potential variation. We also consider local methods of magnetic measurements based on the spin Hall effects and NV-centers. Several scanning probe magnetometers-microscopes are considered, such as magnetic resonance force microscope, SQUID-microscope, and Hall microscope. The review focuses on the spin magnetization measurements of electrons in non-magnetic materials and artificial systems, particularly, in low-dimensional electron systems in semiconductors and in nanosystems, which came to the forefront in recent years.

Synthesis and coherent properties of 13C-enriched sub-micron diamond particles with nitrogen vacancy color centers

Here we report the synthesis of 13C-enriched diamond powder with sub-micron particle sizes via High Pressure High Temperature (HPHT) growth. Diamond powder with a tailored isotopic enrichment is particularly interesting for implementation of Dynamic Nuclear spin Polarization (DNP) and 13C enrichment plays an important role for increasing the signal to noise ratio in Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging. We applied Electron Paramagnetic Resonance (EPR) and NMR spectroscopy to the sub-micron diamond material as well as Optically Detected Magnetic Resonance (ODMR) and atomic force microscopy to investigate preselected nano-sized particles. The 13C spin concentrations were evaluated with NMR for the initial particle ensemble and with ODMR for the nanodiamond fraction, showing the homogeneous distribution of 13C density in particles with different sizes. The 13C nuclear spin-lattice relaxation decay (T1) shows a multiexponential behavior, where the fast relaxing component is attributed to relaxation from surface defects. Additionally, an optical method for estimating the NV− concentration in nanodiamonds is presented. The obtained powder is promising as a base material for the production of 13C-enriched nanodiamonds for DNP applications.

Poly(vinyl alcohol) Membranes Cross‐linked with Maleic Anhydride and 2,5‐Furandicarboxylic Acid: Conventional Heating and Microwave Irradiation

AbstractPoly(vinyl alcohol) (PVA) was cross‐linked with maleic anhydride (MA) and 2,5‐furandicarboxylic acid (FDCA) under conventional heating (CH) and microwave irradiation (MW) to obtain different membranes of PVA/MA and PVA/FDCA modified by the cross‐linking agent concentration, reaction time and type of activation method. The influence of the latter parameters, was studied by comparing the swelling degree of the membranes, swelling kinetics, solubility parameter (δ), Flory interaction parameter (χ12), molecular weight between cross‐links (Mc) and the fractional free volume (FFV).Conditions to cross‐link the membranes were chosen from swelling percentage tests and the samples with the lowest water uptake were characterized by means of Fourier transform infrared spectroscopy (FTIR), 13C nuclear magnetic resonance (13C NMR), thermogravimetric analysis (TGA) and atomic force microscopy (AFM). MW activation used from 23 to 30 minutes to cross‐link the membranes, meanwhile, conventionally heated samples were introduced in an oven for 120 min, meaning that MW activation provided high reaction yields in shorter times. For both activation methods, FTIR spectra recorded peaks in an interval of 1706–1713 cm−1, and 13C NMR presented signals from 162 to 171 ppm, meaning that carbonyl groups from esters were formed. AFM images showed that the rise in roughness was not necessarily directly proportional to the increase in the concentration of cross‐linking agent.

Measuring the temperature of the spin via weak measurement

In this study, we give a new proposal to measure the temperature of the spin in a sample in a magnetic resonance force microscopy system by using postselected weak measurement, and investigating the Fisher information to estimate the precision of the scheme. We show that in a high temperature regime the temperature of the spin can be measured via a weak measurement technique with proper postselection and our scheme is able to increase the precision of temperature estimation.

Anti-proliferative profile of Anacardium occidentale polysaccharide and characterization by AFM

This paper explores the application of cashew gum (CG) as an in vitro antiproliferative, firstly by isolating and characterizing the gum using elemental analysis, gel-permeation chromatography, nuclear magnetic resonance (NMR) and atomic force microscopy (AFM). The molar mass of isolated CG was in the order of 103–104 g/mol, with small protein traces present. Polymer characterization by NMR identified key signals correlating to galactose, glucose, rhamnose and acid-related groups. Three distinct conformational stages were observed by AFM. The impact of CG on cell morphology and viability with both tumor and non-tumor cell lines was studied by AFM and 3-(4,5-dimethyl-2-thiazole)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay respectively. Antiproliferative activity was confirmed for HCT116 (colorectal carcinoma), B16F10 (melanoma) and HL60 (promyelocytic leukemia) cancer cell lines. A change in cell morphology was demonstrated as an increased surface roughness for HL60. Considering that a CG does not exhibit cytotoxicity to non-tumor lines, it can be seen that the CG shows selectivity for tumor cells and can be a promising biomaterial for future studies.

Local and global bifurcations in magnetic resonance force microscopy

The focus of this paper is on the investigation of local and global bifurcations in a continuum mechanics-based resonator model proposed for measurement of electron spin via magnetic resonance force microscopy (MRFM). The resonator model, derived using the extended Hamilton’s principle incorporating the Bloch equations for magnetization, is investigated analytically and numerically. Analysis of both adiabatic and non-adiabatic equilibrium configurations enables formulation of the dynamical system bifurcation structure and identification of the parameter space required for stable MRFM operation. A multiple-scales analysis of the limiting adiabatic model enables estimation of the local bifurcation thresholds for bistable solutions and prediction of the frequency shift that enables spin detection. Orbital instabilities of the adiabatic model reveal a global bifurcation structure where lengthy chaotic transients occur below a homoclinic jump-to-contact threshold which is determined via a Melnikov–Holmes analysis. Both local and global bifurcations are verified numerically in the non-adiabatic model and reveal a dense power spectra for the magnetic moments. The computation of the parameter space governing the model orbital instabilities enables a consistent estimation of robust MRFM operation conditions.

Simulation of the Interaction of a Magnetic Resonance Force Microscope Probe with a Ferromagnetic Sample

We propose an algorithm and present results of micromagnetic simulation of the resonant response of a probe pickup (cantilever) of a magnetic resonance force microscope. Simulation of induced oscillations of sample magnetization makes it possible to calculate the varying component of the force exerted on the probe by the sample and to construct spectra in the form of dependences of the amplitude of oscillations of the cantilever on the external magnetic field strength. Simulation of time dependences of all magnetization field components makes it possible to analyze the spatial distributions of spin-wave resonances of samples. For test objects in the form of rectangular permalloy microstrips, good agreement between model and experimental spectra is achieved.

Method to test Lorentz invariance in electron-capture decay by measuring a neutrino recoil force

Due to hypothetical Loretz invariance violation, additional terms arise in the differential rate for neutrino radiation accompanying electron capture by polarized nuclei. These terms, as well as the parity-violating term, can be probed by measurement of a small recoil force acting on a radioactive sample. An expression for this force is obtained for the case of allowed Gamow–Teller transitions. We discuss prospects to measure the force by using the methods of the magnetic resonance force microscopy, present a list of the most suitable isotopes and give the numerical estimates for mass and activity of required radioactive samples.

Magnetic Resonance Force Microscopy with a One-Dimensional Resolution of 0.9 Nanometers.

Magnetic resonance force microscopy (MRFM) is a scanning probe technique capable of detecting MRI signals from nanoscale sample volumes, providing a paradigm-changing potential for structural biology and medical research. Thus far, however, experiments have not reached sufficient spatial resolution for retrieving meaningful structural information from samples. In this work, we report MRFM imaging scans demonstrating a resolution of 0.9 nm and a localization precision of 0.6 nm in one dimension. Our progress is enabled by an improved spin excitation protocol furnishing us with sharp spatial control on the MRFM imaging slice, combined with overall advances in instrument stability. From a modeling of the slice function, we expect that our arrangement supports spatial resolutions down to 0.3 nm given sufficient signal-to-noise ratio. Our experiment demonstrates the feasibility of subnanometer MRI and realizes an important milestone toward the three-dimensional imaging of macromolecular structures.

Manifestation of ferromagnetic resonance of permalloy microstripes in magnetic force spectroscopy measurements

Abstract Ferromagnetic resonance (FMR) of individual permalloy microstripe is investigated by magnetic resonance force microscopy (MRFM) in the geometry when a probe magnetic moment is parallel to a sample. Three resonant dips in the MRFM spectrum are observed, the lateral shift of the probe relatively to the microstripe leads to consequent transformation of the dips into peaks. This change of the contribution of the same FMR mode in the MRFM spectrum is explained by the change of the phase between magnetic and nonmagnetic probe-sample interaction due to inhomogeneity of the probe magnetic field. Developed micromagnetic simulations of MRFM signal are in a good agreement with experimental data and allow one to analyze the spatial distributions of magnetization oscillations corresponding to the experimental resonant modes.

Spin detection with a micromechanical trampoline: towards magnetic resonance microscopy harnessing cavity optomechanics

We explore the prospects and benefits of combining the techniques of cavity optomechanics with efforts to image spins using magnetic resonance force microscopy (MRFM). In particular, we focus on a common mechanical resonator used in cavity optomechanics—high-stress stoichiometric silicon nitride (Si3N4) membranes. We present experimental work with a ‘trampoline’ membrane resonator that has a quality factor above 106 and an order of magnitude lower mass than a comparable standard membrane resonators. Such high-stress resonators are on a trajectory to reach 0.1 force sensitivities at MHz frequencies by using techniques such as soft clamping and phononic-crystal control of acoustic radiation in combination with cryogenic cooling. We present a demonstration of force-detected electron spin resonance of an ensemble at room temperature using the trampoline resonators functionalized with a magnetic grain. We discuss prospects for combining such a resonator with an integrated Fabry–Perot cavity readout at cryogenic temperatures, and provide ideas for future impacts of membrane cavity optomechanical devices on MRFM of nuclear spins.

Feasibility of imaging in nuclear magnetic resonance force microscopy using Boltzmann polarization

We report on magnetic resonance force microscopy measurements of the Boltzmann polarization of nuclear spins in copper by detecting the frequency shift of a soft cantilever. We use the time-dependent solution of the Bloch equations to derive a concise equation describing the effect of radio-frequent (RF) magnetic fields on both on- and off-resonant spins in high magnetic field gradients. We then apply this theory to saturation experiments performed on a 100 nm thick layer of copper, where we use the higher modes of the cantilever as a source of the RF field. We demonstrate a detection volume sensitivity of only (40nm)3, corresponding to about 1.6×104 polarized copper nuclear spins. We propose an experiment on protons where, with the appropriate technical improvements, frequency-shift based magnetic resonance imaging with a resolution better than (10nm)3 could be possible. Achieving this resolution would make imaging based on the Boltzmann polarization competitive with the more traditional stochastic spin-fluctuation based imaging, with the possibility to work at millikelvin temperatures.

Flux compensation for SQUID-detected Magnetic Resonance Force Microscopy

One of the major challenges in performing SQUID-detected Magnetic Resonance Force Microscopy (MRFM) at milliKelvin temperatures is the crosstalk between the radiofrequency (RF) pulses used for the spin manipulation and the SQUID-based detection mechanism. Here we present an approach based on balancing the flux crosstalk using an on-chip feedback coil coupled to the SQUID. This approach does not require any additional components near the location of the sample, and can therefore be applied to any SQUID-based detection scheme to cancel predictable RF interference. We demonstrate the effectiveness of our approach by showing that we can almost completely negate flux crosstalk with an amplitude of up to several Φ0. This technical achievement allows for complicated magnetic resonance protocols to be performed at temperatures below 50 mK.

Microscale 3D imaging by magnetic resonance force microscopy using full-volume Fourier- and Hadamard-encoding.

Three-dimensional spatially resolved full-volume imaging by magnetic resonance force microscopy at room temperature is described. Spatial resolution in z-dimension is achieved by using the magnetic-field gradient of a ferromagnetic particle that is also used for the force detection of the magnetic resonance. The gradient of the radiofrequency pulses generated by two separate wire-bonded microcoils is used for spatial resolution in x- and y-dimension. To enhance the sensitivity of our measurement Hadamard- and Fourier-encoding schemes are applied due to their multiplex effect. Measurements were taken on a patterned (NH4)2SO4 crystal sample. From the calculated magnetic field distributions, a 3D image was reconstructed with a voxel volume of about 5 μm3 (1.2 μm × 3.0 μm × 1.4 μm in x-, y- and z-dimension).

Моделирование взаимодействия зонда магнитно-резонансного силового микроскопа с ферромагнитным образцом

We report the calculating algorithm and micromagnetic simulation of the resonance response of a magnetic resonance force microscope (MRFM) probe sensor. The simulation of the sample magnetization forced oscillations enables calculating the alternating component of the probe-sample force interaction and to draw the MRFM spectrum in the form of the dependence of cantilever oscillation amplitude on an external magnetic field. In addition, the simulation of the time dependences for all components of the magnetization allows the analysis of spatial distributions for spin-wave resonances in the samples. For the test object in the form of rectangular permalloy microstrips a good agreement between model and experimental MRFM spectra was observed.

Detection of liquids by magnetic resonance force microscopy in the gradient-on-cantilever geometry.

We demonstrate the detection of picoliter amounts of water and triethylenetetramine by a magnetic-resonance-force-microscopy (MRFM) setup operated in the gradient-on-cantilever geometry at room temperature. A magnetic field gradient is produced by a ferromagnetic SmCo particle glued to the tip of a micromechanical resonator (cantilever). The liquids are enclosed in a micro-capillary to protect them from the high vacuum environment needed for sensitive detection. We describe simple spectroscopic experiments as proton T1 - relaxation, Rabi nutation curves and Hahn-echo measurements.