QUENCHING OF THE HALL RESISTANCE IN A NOVEL GEOMETRY

1991 ◽  
Vol 05 (01) ◽  
pp. 21-37
Author(s):  
A.M. CHANG
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electron Beams ◽  
Hall Resistance ◽  
Geometric Structures ◽  
Ballistic Electron ◽  
Junction Geometry ◽  
Side Walls ◽  
Low Magnetic Field ◽  
Heterostructure Devices

We review experiments on the observation of Hall resistance anomalies in ballistic Hall junctions of novel geometries, in submicron GaAs-Al x Ga 1−x As heterostructure devices. We demonstrate that the low magnetic field Hall resistance is greatly influenced by the junction geometry, and that particular geometries are required to give rise to a phenomenon known as “quenching” of the Hall resistance where the conventional linear Hall resistance is suppressed to nearly zero, and to a related plateau feature at slightly higher magnetic fields, known as the “last plateau.” These anomalies are explained in terms of the collimation of ballistic electron beams by specific geometric structures and the scattering properties of the Hall junction side walls.

scholarly journals Dynamics of an orbital polarization of twisted electron beams in electric and magnetic fields

2019 ◽  
Vol 204 ◽  
pp. 10008
Author(s):  
Alexander J. Silenko ◽  
Pengming Zhang ◽  
Liping Zou
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Magnetic Fields ◽  
Quantum Dynamics ◽  
Electron Beams ◽  
Equations Of Motion ◽  
Vortex Beam ◽  
Dirac Particles ◽  
Electric And Magnetic Fields ◽  
Average Projection

Relativistic classical and quantum dynamics of twisted (vortex) Dirac particles in arbitrary electric and magnetic fields is constructed. The relativistic Hamiltonian and equations of motion in the Foldy-Wouthuysen representation are derived. Methods for the extraction of an electron vortex beam with a given orbital polarization and for the manipulation of such a beam are developed. The new effect of a radiative orbital polarization of a twisted electron beam in a magnetic field resulting in a nonzero average projection of the intrinsic orbital angular momentum on the field direction is predicted.

scholarly journals Effect of Low Magnetic Field on Biomimetic Deposition of Hydroxyapatite on Titanium and BIOLINE Stainless Steel

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1484
Author(s):  
Rafael Uribe ◽  
Andrea Uvillús ◽  
Omar Bonilla ◽  
Luis Lascano ◽  
Gema González
Keyword(s):  
Magnetic Field ◽  
Contact Angle ◽  
Stainless Steel ◽  
Magnetic Fields ◽  
Body Fluid ◽  
Metallic Substrates ◽  
Physiological Conditions ◽  
Low Magnetic Field ◽  
Biomimetic Deposition

In this work, we evaluated the effect of a low magnetic field on the deposition of hydroxyapatite (HAp) on different metallic substrates. The substrates studied were titanium and BIOLINE stainless steel SS316LVM with and without Ta and TaN/Ta coatings. Before deposition, the uncoated Ti and SS316LVM substrates were treated with alkali to improve the adhesion of the films prompted to be formed. Next, all substrates (coated and uncoated) were immersed in stimulated body fluid (SBF) at physiological conditions of 37 °C, pH = 7.4, in the presence of magnetic fields from 0.15 T and 0.22 T for 7, 10, and 14 days. The formed films were characterized using SEM, FTIR, and the contact angle. Ti and SS316LVM substrates presented Ca/P relations closer to the stoichiometric HAp. It was demonstrated that in both coatings, Ta and Ta/N, an increase of the bioactivity was obtained. Additionally, our results showed that the application of magnetic fields has a significant effect on the increment in the mass:area ratio of HAp. Finally, the contact angle values were lower than 90°, showing an increase in hydrophilicity with respect to the metallic substrates.

scholarly journals SIMILARITIES OF SGRs WITH LOW MAGNETIC FIELD AND WHITE DWARF PULSARS

2012 ◽  
Vol 18 ◽  
pp. 96-100 ◽  
Author(s):  
J. G. COELHO ◽  
M. MALHEIRO
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
White Dwarf ◽  
Alternative Explanation ◽  
Gamma Ray ◽  
Strong Magnetic Fields ◽  
X Ray ◽  
Surface Magnetic Field ◽  
Astrophysical Objects ◽  
Low Magnetic Field

Some of the most interesting types of astrophysical objects that have been intensively studied in the recent years are the Anomalous X-ray Pulsars (AXPs) and Soft Gamma-ray Repeaters (SGRs) seen usually as neutron stars pulsars with super strong magnetic fields. However, in the last two years two SGRs with low magnetic fields have been detected. Moreover, fast and very magnetic white dwarf pulsars have also been observed in the last years. Based on these new pulsar discoveries, white dwarf pulsars have been proposed as an alternative explanation to the observational features of SGRs and AXPs. Here we present several properties of these SGRs/AXPs as WD pulsar, in particular the surface magnetic field and the magnetic dipole momentum.

Effects of Low Magnetic Fields on Gold-YBCO Contacts

1989 ◽  
Vol 169 ◽  
Author(s):  
Yonhua Tzeng ◽  
Mitchell A. Belser
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Electrical Properties ◽  
Magnetic Fields ◽  
Contact Resistance ◽  
High Magnetic Field ◽  
High Current ◽  
Long Time ◽  
Low Magnetic Field ◽  
The Magnetic Field

AbstractThe effects of low magnetic field (0–40 Gauss) on electrical properties of gold-YBCO contacts are investigated. The contact resistance increases significantly with applied magnetic fields. For high magnetic field or when high current is flowing through the contact, the contact resistance decays after removing the magnetic field to a finite value greater than that is measured before the contact is exposed to the magnetic field and stays there for long time as long as the sample is kept below the superconductivity critical temperature.

scholarly journals Radio-continuum surveys with SKA and LOFAR: a first look at the perspectives for radio mini-halos

2018 ◽  
Vol 617 ◽  
pp. A11 ◽  
Author(s):  
M. Gitti ◽  
G. Brunetti ◽  
R. Cassano ◽  
S. Ettori
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
High Redshift ◽  
Low Frequency ◽  
Physical Nature ◽  
Radio Continuum ◽  
X Ray ◽  
Statistical Studies ◽  
Low Magnetic Field ◽  
First Time

Context. Diffuse synchrotron radio emission has been observed in a number of cool-core clusters on scales comparable to that of the cooling region. These radio sources are called “mini-halos”. In order to understand their origin, which is still unclear, joint radio and X-ray statistical studies of large cluster samples are necessary to investigate the radio mini-halo properties and their connection with the cluster thermodynamics. Aims. We here extend our previous explorative study and investigate the perspectives offered by surveys in the radio continuum with the LOw Frequency ARray (LOFAR) and the Square Kilometre Array (SKA), in particular examining the effect of the intracluster magnetic field in the mini-halo region for the first time. Methods. By considering the minimum flux detectable in radio surveys and exploiting the Pradio − LX correlation observed for known mini-halos, we estimate the detection limits achievable by future radio observational follow-up of X-ray cluster samples, such as HIFLUGCS and eROSITA. This allows us to estimate the maximum number of radio mini-halos that can potentially be discovered in future surveys as a function of redshift and magnetic field strength. Results. Under the optimistic assumption that all cool-core systems host a mini-halo and that the radio versus X-ray scaling relation extends to systems with lower X-ray luminosity, we show that future radio surveys with LOFAR and SKA1 (at ∼140 MHz and ∼1.4 GHz) have the potential to discover ∼1000–10 000 radio mini-halo candidates up to redshift z =  1. This shows that these surveys may be able to produce a breakthrough in the study of these sources. We further note that future SKA1 radio surveys at redshift z > 0.6 will allow us to distinguish between different magnetic fields in the mini-halo region, because higher magnetic fields are expected to produce more powerful mini-halos, thus implying a larger number of mini-halo candidates detected at high redshift. For example, the non-detection with SKA1 of mini-halos at z > 0.6 will suggest a low magnetic field (B < few μG). The synergy of these radio surveys with future X-ray observations and theoretical studies is essential in establishing the radio mini-halo physical nature.

Field Dependence of Meissner Effect in a Single Crystal of YBa2Cu3Ox in the Ultra-Low Magnetic Field Regime

1987 ◽  
Vol 99 ◽  
Author(s):  
L. Krusin-Elbaum ◽  
A. P. Malozemoff ◽  
Y. Yeshurun
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystal ◽  
Field Dependence ◽  
Flux Pinning ◽  
Strong Field ◽  
Meissner Effect ◽  
Glassy Behavior ◽  
Low Magnetic Field ◽  
Flux Expulsion

ABSTRACTWe report a strong field-dependence (from 0.1% to 71%) of flux expulsion (Meissner effect) in a single crystal of YBa2Cu3Ox in magnetic fields from 36 kOe down to 50 mOe. The data is discussed in the context of flux pinning forces and glassy behavior.

scholarly journals Designing a Planar Fluxgate Using the PCB Technology

2021 ◽  
Vol 12 (2) ◽  
pp. 117-123
Author(s):  
A. A. Kolomeitsev ◽  
I. A. Zatonov ◽  
M. I. Pischanskaya ◽  
P. F. Baranov ◽  
D. P. Ilyaschenko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Microelectromechanical Systems ◽  
Second Harmonic ◽  
Temperature Stability ◽  
Weak Magnetic Fields ◽  
Channel Temperature ◽  
Space Objects ◽  
Low Magnetic Field ◽  
Equipment And Instruments

The development of novel methods, scientific devices and means for measuring magnetic fields generated by ultra-low current is among promising directions in the development of medical equipment and instruments for geodetic surveys and space exploration. The present work is to develop a small sensor capable of detecting weak magnetic fields, which sources are biocurrents, radiation of far space objects and slight fluctuations of the geomagnetic field. Scientists estimate the strength of such magnetic fields as deciles of nanotesla. The key requirements for the sensors of ultra-low magnetic field are: resolution, noise level in the measurement channel, temperature stability, linearity and repeatability of the characteristics from one produced item to another. The aforementioned characteristics can be achieved by using planar technologies and microelectromechanical systems (MEMS) in such advanced sensors.The work describes a complete R&D cycle, from creating the computer model of the sensor under study to manufacturing of a working prototype. To assess the effect of the geometry and material properties, the Jiles–Atherton model is implemented which, unlike the majority of the models used, allows considering the non-linearity of the core, its hysteresis properties and influence of residual magnetization.The dimensions of the developed sensor are 40×20×5 mm, while the technology allows its further diminishment. The sensor has demonstrated the linearity of its properties in the range of magnetic field strength from 0.1 nT to 50 µT for a rms current of excitation of 1.25 mA at a frequency of 30 kHz. The average sensitivity for the second harmonic is 54 µV/nT.

scholarly journals Magnetic-field-induced robust zero Hall plateau state in MnBi2Te4 Chern insulator

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chang Liu ◽  
Yongchao Wang ◽  
Ming Yang ◽  
Jiahao Mao ◽  
Hao Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Theoretical Calculations ◽  
Zeeman Effect ◽  
Hall Resistance ◽  
Edge States ◽  
Transport Studies ◽  
Topological Quantum ◽  
Plateau State ◽  
Quantum Phenomena

AbstractThe intrinsic antiferromagnetic topological insulator MnBi2Te4 provides an ideal platform for exploring exotic topological quantum phenomena. Recently, the Chern insulator and axion insulator phases have been realized in few-layer MnBi2Te4 devices at low magnetic field regime. However, the fate of MnBi2Te4 in high magnetic field has never been explored in experiment. In this work, we report transport studies of exfoliated MnBi2Te4 flakes in pulsed magnetic fields up to 61.5 T. In the high-field limit, the Chern insulator phase with Chern number C = −1 evolves into a robust zero Hall resistance plateau state. Nonlocal transport measurements and theoretical calculations demonstrate that the charge transport in the zero Hall plateau state is conducted by two counter-propagating edge states that arise from the combined effects of Landau levels and large Zeeman effect in strong magnetic fields. Our result demonstrates the intricate interplay among intrinsic magnetic order, external magnetic field, and nontrivial band topology in MnBi2Te4.

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.

Sign in / Sign up

Export Citation Format

Share Document