scholarly journals Instability caused swimming of ferromagnetic filaments in pulsed field

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdelqader Zaben ◽  
Guntars Kitenbergs ◽  
Andrejs Cēbers
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Numerical Simulations ◽  
Wave Field ◽  
Duty Cycle ◽  
Pulse Wave ◽  
Medical Applications ◽  
Field Profile ◽  
Pulsed Field ◽  
Good Agreement

AbstractMagnetic filaments driven by external magnetic field are an interesting topic of research in-terms of the possible bio-medical applications. In this paper, we investigated the applicability of using ferromagnetic filaments as micro swimmers both experimentally and numerically. It was found that applying a pulse wave field profile with a duty cycle of 30$$\%$$ % induced experimentally observable swimming, which is similar to the breast stroke of micro algae. Good agreement with numerical simulations was found. Moreover, for stable continuous swimming, an initial filament shape is required to avoid transition to the structurally preferred non-swimming S-like mode.

Viscomagnetic Heat Flux Experiments as a Test of Gas Kinetic Theory in the Burnett Regime

1978 ◽  
Vol 33 (7) ◽  
pp. 749-760 ◽  
Author(s):  
G. E. J. Eggermont ◽  
P. W. Hermans ◽  
L. J. F. Hermans ◽  
H. F. P. Knaap ◽  
J. J. M. Beenakker
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Heat Flux ◽  
External Magnetic Field ◽  
Room Temperature ◽  
Flow Direction ◽  
Rectangular Channel ◽  
Gas Kinetic Theory ◽  
The Magnetic Field ◽  
Good Agreement

In a rarefied polyatomic gas streaming through a rectangular channel, an external magnetic field produces a heat flux perpendicular to the flow direction. Experiments on this “viscom agnetic heat flux” have been performed for CO, N2, CH4 and HD at room temperature, with different orientations of the magnetic field. Such measurements enable one to separate the boundary layer contribution from the purely bulk contribution by means of the theory recently developed by Vestner. Very good agreement is found between the experimentally determined bulk contribution and the theoretical Burnett value for CO, N2 and CH4 , yet the behavior of HD is found to be anomalous.

The mmW Band Tamm States in One-Dimensional Magnetophotonic Crystals

2009 ◽  
Vol 152-153 ◽  
pp. 394-396 ◽  
Author(s):  
Sergey I. Tarapov ◽  
M. Khodzitskiy ◽  
S.V. Chernovtsev ◽  
D. Belosorov ◽  
A.M. Merzlikin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Theoretical Prediction ◽  
Experimental Results ◽  
One Dimensional ◽  
Magnetophotonic Crystals ◽  
Good Agreement

The mmW band photonic Tamm states in 1D magnetophotonic crystals are studied. It is shown the possibility to manipulate the eigenfrequencies of such states by an external magnetic field. Our experimental results are in a good agreement with theoretical prediction.

Observations and simulations of foreshock waves during magnetic clouds

2020 ◽  
Author(s):  
Lucile Turc ◽  
Owen Roberts ◽  
Martin Archer ◽  
Minna Palmroth ◽  
Markus Battarbee ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Numerical Simulations ◽  
Wave Field ◽  
Geomagnetic Storms ◽  
Wave Activity ◽  
Bow Shock ◽  
Magnetic Clouds ◽  
Direction Parallel ◽  
High Magnetic Field Strength ◽  
The Waves

<p>The foreshock is a region of intense wave activity, situated upstream of the quasi-parallel sector of the terrestrial bow shock. The most common type of waves in the Earth's ion foreshock are quasi-monochromatic fast magnetosonic waves with a period of about 30 s. In this study, we investigate how the foreshock wave field is modified when magnetic clouds, a subset of coronal mass ejections driving the most intense geomagnetic storms, interact with near-Earth space. Using observations from the Cluster constellation, we find that the average period of the fast magnetosonic waves is significantly shorter than the typical 30 s during magnetic clouds, due to the high magnetic field strength inside those structures, consistent with previous works. We also show that the quasi-monochromatic waves are replaced by a superposition of waves at different frequencies. Numerical simulations performed with the hybrid-Vlasov model Vlasiator consistently show that an enhanced upstream magnetic field results in less monochromatic wave activity in the foreshock. The global view of the foreshock wave field provided by the simulation further reveals that the waves are significantly smaller during magnetic clouds, both in the direction parallel and perpendicular to the wave vector. We estimate the transverse extent of the waves using a multi-spacecraft analysis technique and find a good agreement between the numerical simulations and the spacecraft measurements. This suggests that the foreshock wave field is structured over smaller scales during magnetic clouds. These modifications of the foreshock wave properties are likely to affect the regions downstream - the bow shock, the magnetosheath and possibly the magnetosphere - as foreshock waves are advected earthward by the solar wind.</p>

Multifractal Specific Heat of Disordered Mesoscopic Systems

1998 ◽  
Vol 12 (01) ◽  
pp. 11-15 ◽  
Author(s):  
A. Bershadskii
Keyword(s):  
Magnetic Field ◽  
Numerical Simulations ◽  
Specific Heat ◽  
High Magnetic Field ◽  
Critical Behavior ◽  
Two Dimensional ◽  
Mesoscopic Systems ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Good Agreement

It is shown that multifractal data on critical behavior of wavefunctions at the Anderson metal–insulator transition obtained in numerical simulations are in good agreement with constant specific-heat multifractal approximation for three and two dimensional cases (in the last case in high magnetic field). A relation of this approximation to the parabolic multifractal approximation is also briefly discussed.

The thickness of perpendicular collisionless shocks in a hot plasma

1972 ◽  
Vol 8 (2) ◽  
pp. 137-142 ◽  
Author(s):  
R. A. Cairns
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Wave Front ◽  
Characteristic Length ◽  
Magnetic Pressure ◽  
Collisionless Shocks ◽  
Hot Plasma ◽  
Shock Thickness ◽  
Good Agreement

By linearizing about the upstream state, the characteristic length for the growth of magnetic field in a laminar wave front, propagating perpendicular to an external magnetic field, is found as a function of βi, the ratio of ion pressure to magnetic pressure. For values of βi, between 10–2 and 1 the thickness is found to scale as . This scaling is in good agreement with the observed scaling of turbulent shocks, suggesting that for such shocks the shock thickness is closely related to that of the corresponding laminar pulse.

scholarly journals Моделирование взаимодействия зонда магнитно-резонансного силового микроскопа с ферромагнитным образцом

2019 ◽  
Vol 89 (11) ◽  
pp. 1646
Author(s):  
Р.В. Горев ◽  
Е.В. Скороходов ◽  
В.Л. Миронов
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Oscillation Amplitude ◽  
Forced Oscillations ◽  
Spatial Distributions ◽  
Force Interaction ◽  
Resonance Response ◽  
Magnetic Resonance Force Microscope ◽  
Probe Sensor ◽  
Good Agreement

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.

scholarly journals Integrating micromagnets and hybrid nanowires for topological quantum computing

2021 ◽  
Vol 11 (5) ◽  
Author(s):  
Malcolm Jardine ◽  
John Stenger ◽  
Yifan Jiang ◽  
Eline J. de Jong ◽  
Wenbo Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Computing ◽  
External Magnetic Field ◽  
Numerical Simulations ◽  
Hybrid Systems ◽  
Scaling Up ◽  
Magnet Design ◽  
Zero Modes ◽  
Magnetic Imaging ◽  
Topological Quantum

Majorana zero modes are expected to arise in semiconductor-superconductor hybrid systems, with potential topological quantum computing applications. One limitation of this approach is the need for a relatively high external magnetic field that should also change direction at the nanoscale. This proposal considers devices that incorporate micromagnets to address this challenge. We perform numerical simulations of stray magnetic fields from different micromagnet configurations, which are then used to solve for Majorana wavefunctions. Several devices are proposed, starting with the basic four-magnet design to align magnetic field with the nanowire and scaling up to nanowire T-junctions. The feasibility of the approach is assessed by performing magnetic imaging of prototype patterns.

scholarly journals THE QUANTUM HALL EFFECT IN GRAPHENE

2012 ◽  
Vol 26 (13) ◽  
pp. 1250084 ◽  
Author(s):  
PAOLO CEA
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Numerical Simulations ◽  
Hall Effect ◽  
Quantum Hall Effect ◽  
Quantum Hall ◽  
Landau Levels ◽  
Dynamical Generation ◽  
Dirac Sea

We investigate the quantum Hall effect in graphene. We argue that in graphene in presence of an external magnetic field there is dynamical generation of mass by a rearrangement of the Dirac sea. We show that the mechanism breaks the lattice valley degeneracy only for the n = 0 Landau levels and leads to the new observed ν = ±1 quantum Hall plateaus. We suggest that our result can be tested by means of numerical simulations of planar Quantum Electro Dynamics with dynamical fermions in an external magnetic fields on the lattice.

THE SIMULATION OF THE TWO-DIMENSIONAL ISING MODEL IN THE PRESENCE OF AN EXTERNAL MAGNETIC FIELD ON THE CREUTZ CELLULAR AUTOMATON

2000 ◽  
Vol 11 (03) ◽  
pp. 561-572 ◽  
Author(s):  
B. KUTLU ◽  
M. KASAP ◽  
S. TURAN
Keyword(s):  
Magnetic Field ◽  
Ising Model ◽  
External Magnetic Field ◽  
Cellular Automaton ◽  
Critical Behavior ◽  
Finite Size ◽  
Two Dimensional ◽  
Finite Size Scaling ◽  
Creutz Cellular Automaton ◽  
Good Agreement

The two-dimensional Ising model in a small external magnetic field, is simulated on the Creutz cellular automaton. The values of the static critical exponents for 0.0025 ≤ h ≤ 0.025 are estimated within the framework of the finite size scaling theory. The value of the field critical exponent is in a good agreement with its theoretical value of δ = 15. The results for 0.0025 ≤ h ≤ 0.025 are compatible with Ising critical behavior for T < Tc.

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