Influence of Magnetic Fields on Ballistic Transport in Narrow Constrictions

1989 ◽  
pp. 371-374
Author(s):  
B. Huckestein ◽  
R. Johnston ◽  
L. Schweitzer
Keyword(s):  
Magnetic Fields ◽  
Ballistic Transport

scholarly journals Баллистическое течение двумерных электронов в магнитном поле

2021 ◽  
Vol 55 (7) ◽  
pp. 566
Author(s):  
А.Н. Афанасьев ◽  
П.С. Алексеев ◽  
А.А. Грешнов ◽  
М.А. Семина
Keyword(s):  
Magnetic Fields ◽  
Ballistic Transport ◽  
Ballistic Regime ◽  
Electron Collisions ◽  
Viscosity Effect ◽  
Small Density ◽  
Longitudinal Resistance ◽  
Analytical Formulas ◽  
Sample Width ◽  
Theoretical Results

In conductors with a very small density of defects, electrons at low temperatures collide predominantly with a sample edges. Therefore, the ballistic regime of charge and heat transport is realized. The application of a perpendicular magnetic field substantially modifies the character of ballistic transport. For the case of two-dimensional (2D) electrons in the magnetic fields corresponding to the diameter of the cyclotron trajectories smaller than the sample width a hydrodynamic transport regime is formed. In the latter regime, the flow is mainly controlled by rare electron–electron collisions, which determine the viscosity effect. In this work, we study the ballistic flow of 2D electrons in long samples in magnetic fields up to the critical field of the transition to the hydrodynamic regime. From solution of the kinetic equation, we obtain analytical formulas for the profiles of the current density and the Hall electric field far and near the ballistic-hydrodynamic transition as well as for the longitudinal and Hall resistances in these ranges. Our theoretical results, apparently, describe the observed longitudinal resistance of pure graphene samples in the diapason of magnetic fields below the ballistic-hydrodynamic transition.

scholarly journals Minibands in twisted bilayer graphene probed by magnetic focusing

2020 ◽  
Vol 6 (16) ◽  
pp. eaay7838 ◽  
Author(s):  
A. I. Berdyugin ◽  
B. Tsim ◽  
P. Kumaravadivel ◽  
S. G. Xu ◽  
A. Ceferino ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Magnetic Fields ◽  
Long Range ◽  
Electron Scattering ◽  
Low Temperatures ◽  
Ballistic Transport ◽  
Bilayer Graphene ◽  
Degree Of Freedom ◽  
Magnetic Focusing ◽  
Twisted Bilayer Graphene

Magnetic fields force ballistic electrons injected from a narrow contact to move along skipping orbits and form caustics. This leads to pronounced resistance peaks at nearby voltage probes as electrons are effectively focused inside them, a phenomenon known as magnetic focusing. This can be used not only for the demonstration of ballistic transport but also to study the electronic structure of metals. Here, we use magnetic focusing to probe narrowbands in graphene bilayers twisted at ~2°. Their minibands are found to support long-range ballistic transport limited at low temperatures by intrinsic electron-electron scattering. A voltage bias between the layers causes strong minivalley splitting and allows selective focusing for different minivalleys, which is of interest for using this degree of freedom in frequently discussed valleytronics.

Semiclassical Ballistic Transport through a Circular Microstructure in Weak Magnetic Fields

2013 ◽  
Vol 30 (4) ◽  
pp. 040501 ◽  
Author(s):  
Yan-Hui Zhang ◽  
Xiang-Ji Cai ◽  
Zong-Liang Li ◽  
Guo-Hui Jiang ◽  
Qin-Nan Yang ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Ballistic Transport ◽  
Weak Magnetic Fields

Ballistic transport through GaAs–AlGaAs superlattices in transverse magnetic fields

2000 ◽  
Vol 88 (6) ◽  
pp. 3495-3500 ◽  
Author(s):  
D. Rakoczy ◽  
J. Smoliner ◽  
R. Heer ◽  
G. Strasser
Keyword(s):  
Magnetic Fields ◽  
Ballistic Transport ◽  
Transverse Magnetic

scholarly journals Ballistic transport in random magnetic fields with anisotropic long-ranged correlations

2005 ◽  
Vol 38 (14) ◽  
pp. L235-L240
Author(s):  
Hajo Leschke ◽  
Simone Warzel ◽  
Alexandra Weichlein
Keyword(s):  
Magnetic Fields ◽  
Ballistic Transport

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

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