scholarly journals Mechanical magnetometry of Cobalt nanospheres deposited by focused electron beam at the tip of ultra-soft cantilevers

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Hugo Lavenant ◽  
Vladimir Naletov ◽  
Olivier Klein ◽  
Grégoire de Loubens ◽  
Laura Casado ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Equilibrium Configuration ◽  
Vortex State ◽  
Magnetic Vortex ◽  
Hysteresis Curve ◽  
Focus Electron Beam ◽  
Sem Image ◽  
Magnetic Nanospheres ◽  
Electron Beam Induced Deposition

AbstractUsing focused-electron-beam-induced deposition, Cobalt magnetic nanospheres with diameter ranging between 100 nm and 300 nm are grown at the tip of ultra-soft cantilevers. By monitoring the mechanical resonance frequency of the cantilever as a function of the applied magnetic field, the hysteresis curve of these individual nanospheres are measured. This enables the evaluation of their saturation magnetization, found to be around 430 emu/cm3 independent of the size of the particle, and to infer that the magnetic vortex state is the equilibrium configuration of these nanospheres at remanence.SEM image of a 200 nm Co nanosphere grown at the tip of an ultra-soft cantilever by focus electron beam induced deposition.

scholarly journals Magnetic properties of optimized cobalt nanospheres grown by focused electron beam induced deposition (FEBID) on cantilever tips

2017 ◽  
Vol 8 ◽  
pp. 2106-2115 ◽  
Author(s):  
Soraya Sangiao ◽  
César Magén ◽  
Darius Mofakhami ◽  
Grégoire de Loubens ◽  
José María De Teresa
Keyword(s):  
Magnetic Properties ◽  
Electron Beam ◽  
Saturation Magnetization ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Cobalt Content ◽  
Vortex State ◽  
Magnetic Vortex ◽  
Electron Holography ◽  
Electron Beam Induced Deposition

In this work, we present a detailed investigation of the magnetic properties of cobalt nanospheres grown on cantilever tips by focused electron beam induced deposition (FEBID). The cantilevers are extremely soft and the cobalt nanospheres are optimized for magnetic resonance force microscopy (MRFM) experiments, which implies that the cobalt nanospheres must be as small as possible while bearing high saturation magnetization. It was found that the cobalt content and the corresponding saturation magnetization of the nanospheres decrease for nanosphere diameters less than 300 nm. Electron holography measurements show the formation of a magnetic vortex state in remanence, which nicely agrees with magnetic hysteresis loops performed by local magnetometry showing negligible remanent magnetization. As investigated by local magnetometry, optimal behavior for high-resolution MRFM has been found for cobalt nanospheres with a diameter of ≈200 nm, which present atomic cobalt content of ≈83 atom % and saturation magnetization of 106 A/m, around 70% of the bulk value. These results represent the first comprehensive investigation of the magnetic properties of cobalt nanospheres grown by FEBID for application in MRFM.

scholarly journals Resonantly excited precession motion of three-dimensional vortex core in magnetic nanospheres

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Sang-Koog Kim ◽  
Myoung-Woo Yoo ◽  
Jehyun Lee ◽  
Ha-Youn Lee ◽  
Jae-Hyeok Lee ◽  
...  
Keyword(s):  
Vortex Core ◽  
Three Dimensional ◽  
Vortex State ◽  
Static Field ◽  
Angular Frequency ◽  
Magnetic Vortex ◽  
Gyromagnetic Ratio ◽  
Sphere Diameter ◽  
Magnetic Nanospheres ◽  
Particle Resonance

Abstract We found resonantly excited precession motions of a three-dimensional vortex core in soft magnetic nanospheres and controllable precession frequency with the sphere diameter 2R, as studied by micromagnetic numerical and analytical calculations. The precession angular frequency for an applied static field H DC is given as ωMV = γeff H DC, where γeff = γ〈m Γ〉 is the effective gyromagnetic ratio in collective vortex dynamics, with the gyromagnetic ratio γ and the average magnetization component 〈m Γ〉 of the ground-state vortex in the core direction. Fitting to the micromagnetic simulation data for 〈m Γ〉 yields a simple explicit form of 〈m Γ〉 ≈ (73.6 ± 3.4)(l ex /2R)2.20±0.14, where l ex is the exchange length of a given material. This dynamic behavior might serve as a foundation for potential bio-applications of size-specific resonant excitation of magnetic vortex-state nanoparticles, for example, magnetic particle resonance imaging.

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

A Color Coded STEM/SEM Image Storage System

1981 ◽  
Vol 39 ◽  
pp. 272-273
Author(s):  
Y. Kokubo ◽  
W. H. Hardy ◽  
J. Dance ◽  
K. Jones
Keyword(s):  
Image Processing ◽  
Electron Beam ◽  
Storage System ◽  
Particle Analysis ◽  
Specific Information ◽  
X Rays ◽  
Sem Image ◽  
Backscattered Electrons ◽  
Wide Range ◽  
Scanning Electron

A color coded digital image processing is accomplished by using JEM100CX TEM SCAN and ORTEC’s LSI-11 computer based multi-channel analyzer (EEDS-II-System III) for image analysis and display. Color coding of the recorded image enables enhanced visualization of the image using mathematical techniques such as compression, gray scale expansion, gamma-processing, filtering, etc., without subjecting the sample to further electron beam irradiation once images have been stored in the memory.The powerful combination between a scanning electron microscope and computer is starting to be widely used 1) - 4) for the purpose of image processing and particle analysis. Especially, in scanning electron microscopy it is possible to get all information resulting from the interactions between the electron beam and specimen materials, by using different detectors for signals such as secondary electron, backscattered electrons, elastic scattered electrons, inelastic scattered electrons, un-scattered electrons, X-rays, etc., each of which contains specific information arising from their physical origin, study of a wide range of effects becomes possible.

Tuning the Magnetic Vortex State in Magnetite Nanodiscs for Remote Control of Biological Signalling

2019 ◽  
Author(s):  
Danijela Gregurec ◽  
Alexander W. Senko ◽  
Andrey Chuvilin ◽  
Pooja Reddy ◽  
Ashwin Sankararaman ◽  
...  
Keyword(s):  
Remote Control ◽  
Ion Channels ◽  
Ground State ◽  
Magnetic Particles ◽  
Colloidal Stability ◽  
Vortex State ◽  
Magnetic Vortex ◽  
Electron Holography ◽  
Dipole Interactions ◽  
Magnetite Particles

In this work, we demonstrate the application of anisotropic magnetite nanodiscs (MNDs) as transducers of torque to mechanosensory cells under weak, slowly varying magnetic fields (MFs). These MNDs possess a ground state vortex configuration of magnetic spins which affords greater colloidal stability due to eliminated dipole-dipole interactions characteristic of isotropic magnetic particles of similar size. We first predict vortex magnetization using micromagnetic stimulations in sub-micron anisotropic magnetite particles and then use electron holography to experimentally investigate the magnetization of MNDs 98–226 nm in diameter. When MNDs are coupled to MFs, they transition between vortex and in-plane magnetization allowing for the exertion of the torque on the pN scale, which is sufficient to activate mechanosensitive ion channels in cell membranes.<br>

scholarly journals Double layers in the downward current region of the aurora

2003 ◽  
Vol 10 (1/2) ◽  
pp. 45-52 ◽  
Author(s):  
R. E. Ergun ◽  
L. Andersson ◽  
C. W. Carlson ◽  
D. L. Newman ◽  
M. V. Goldman
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Phase Space ◽  
Electric Field ◽  
Electric Fields ◽  
Double Layers ◽  
Parallel Electric Field ◽  
Electrostatic Waves ◽  
Current Region ◽  
Decisive Evidence

Abstract. Direct observations of magnetic-field-aligned (parallel) electric fields in the downward current region of the aurora provide decisive evidence of naturally occurring double layers. We report measurements of parallel electric fields, electron fluxes and ion fluxes related to double layers that are responsible for particle acceleration. The observations suggest that parallel electric fields organize into a structure of three distinct, narrowly-confined regions along the magnetic field (B). In the "ramp" region, the measured parallel electric field forms a nearly-monotonic potential ramp that is localized to ~ 10 Debye lengths along B. The ramp is moving parallel to B at the ion acoustic speed (vs) and in the same direction as the accelerated electrons. On the high-potential side of the ramp, in the "beam" region, an unstable electron beam is seen for roughly another 10 Debye lengths along B. The electron beam is rapidly stabilized by intense electrostatic waves and nonlinear structures interpreted as electron phase-space holes. The "wave" region is physically separated from the ramp by the beam region. Numerical simulations reproduce a similar ramp structure, beam region, electrostatic turbulence region and plasma characteristics as seen in the observations. These results suggest that large double layers can account for the parallel electric field in the downward current region and that intense electrostatic turbulence rapidly stabilizes the accelerated electron distributions. These results also demonstrate that parallel electric fields are directly associated with the generation of large-amplitude electron phase-space holes and plasma waves.

Annealing effect of platinum-incorporated nanowires created by focused ion/electron-beam-induced deposition

2014 ◽  
Vol 23 (8) ◽  
pp. 088111 ◽  
Author(s):  
Jing-Yue Fang ◽  
Shi-Qiao Qin ◽  
Xue-Ao Zhang ◽  
Dong-Qing Liu ◽  
Sheng-Li Chang
Keyword(s):  
Electron Beam ◽  
Annealing Effect ◽  
Electron Beam Induced Deposition

scholarly journals Compton and Raman free electron laser stability properties for a cold electron beam propagating through a helical magnetic wiggler

1985 ◽  
Vol 33 (3) ◽  
pp. 387-423 ◽  
Author(s):  
John A. Davies ◽  
Ronald C. Davidson ◽  
George L. Johnston
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Dispersion Relation ◽  
Free Electron ◽  
Free Electron Laser ◽  
Relativistic Electron Beam ◽  
Cold Electron ◽  
Wiggler Magnetic Field ◽  
Laser Stability

This paper gives an extensive characterization of the range of validity of the Compton and Raman approximations to the exact free electron laser dispersion relation for a cold, relativistic electron beam propagating through a constantamplitude helical wiggler magnetic field. The electron beam is treated as infinite in transverse extent. Specific properties of the exact and approximate dispersion relations are investigated analytically and numerically. In particular, a detailed numerical analysis is carried out to determine the range of validity of the Compton approximation.

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