HALL AND MAGNETORESISTANCE EFFECTS OBTAINED FROM SIMULTANEOUS MEASUREMENTS OF LIQUID METALS AND SEMICONDUCTORS

2004 ◽  
Vol 18 (27n29) ◽  
pp. 3625-3628
Author(s):  
M. OGITA ◽  
T. ITO ◽  
M. ISAI ◽  
I. MOGI ◽  
S. AWAJI ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Liquid Metals ◽  
Simultaneous Methods ◽  
Hall Measurements ◽  
Hall Effects ◽  
Galvanomagnetic Effects ◽  
Liquid States ◽  
Low Magnetic Field ◽  
The Magnetic Field ◽  
Solid And Liquid States

Hall measurements of liquid metals, using two-frequency, ac-dc and simultaneous methods are described. The Hall effect has been measured in Hg and Ga metals, in both solid and liquid states. The magnetoresistance and Hall effects have also been measured in an InSb single crystal, which exhibited magnetoresistance even in low magnetic field, and in Si , which did not exhibit magnetoresistance in low magnetic field. In order to investigate the magnetic field dependence of the observed galvanomagnetic effects for solid and liquid state metals, and for semiconductors, Hall measurements in high magnetic field, up to ±9 T, were also performed.

Effect of magnetic field on parametrically driven surface waves

2006 ◽  
Vol 463 (2079) ◽  
pp. 711-722 ◽  
Author(s):  
Supriyo Paul ◽  
Krishna Kumar
Keyword(s):  
Magnetic Field ◽  
Surface Waves ◽  
Liquid Metals ◽  
Tricritical Point ◽  
Thin Layers ◽  
Vertical Magnetic Field ◽  
Harmonic Solution ◽  
Chandrasekhar Number ◽  
The Magnetic Field ◽  
Primary Instability

Stability analysis of parametrically driven surface waves in liquid metals in the presence of a uniform vertical magnetic field is presented. Floquet analysis gives various subharmonic and harmonic instability zones. The magnetic field stabilizes the onset of parametrically excited surface waves. The minima of all the instability zones are raised by a different amount as the Chandrasekhar number is raised. The increase in the magnetic field leads to a series of bicritical points at a primary instability in thin layers of a liquid metal. The bicritical points involve one subharmonic and another harmonic solution of different wavenumbers. A tricritical point may also be triggered as a primary instability by tuning the magnetic field.

Quantum Hall effects

Quantum 20/20 ◽  
2019 ◽  
pp. 303-322
Author(s):  
Ian R. Kenyon
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Energy Gap ◽  
Quantum Hall ◽  
Free Electrons ◽  
Electron Gases ◽  
Hall Conductance ◽  
Hall Effects ◽  
The Stability ◽  
The Magnetic Field

It is explained how plateaux are seen in the Hall conductance of two dimensional electron gases, at cryogenic temperatures, when the magnetic field is scanned from zero to ~10T. On a Hall plateau σ‎xy = ne 2/h, where n is integral, while the longitudinal conductance vanishes. This is the integral quantum Hall effect. Free electrons in such devices are shown to occupy quantized Landau levels, analogous to classical cyclotron orbits. The stability of the IQHE is shown to be associated with a mobility gap rather than an energy gap. The analysis showing the topological origin of the IQHE is reproduced. Next the fractional QHE is described: Laughlin’s explanation in terms of an IQHE of quasiparticles is presented. In the absence of any magnetic field, the quantum spin Hall effect is observed, and described here. Time reversal invariance and Kramer pairs are seen to be underlying requirements. It’s topological origin is outlined.

scholarly journals Stretching of the Super-Elastic Double-Helix Geon. Wheeler´s Thermal Geons as Quanta of Heat and Momentum. Bohm´s Diffusion and the Heating of the Solar Corona and Heating of the Earth - Geon Engineering. Milgrom-Verlinde Constant. Mareš - Šesták constant

2020 ◽  
Vol 12 (2) ◽  
pp. 12
Author(s):  
Jiri Stavek
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Solar Corona ◽  
Magnetic Field Strength ◽  
Double Helix ◽  
David Bohm ◽  
The Earth ◽  
Highly Sensitive ◽  
Low Magnetic Field ◽  
The Magnetic Field

In our approach we have combined knowledge of Old Masters (working in this field before the year 1905), New Masters (working in this field after the year 1905) and Dissidents under the guidance of Louis de Broglie and David Bohm. Based on the great works of Julian Schwinger and John Archibald Wheeler we will study properties of geons formed by fusion of two soft x-ray particles (dyons) in the Schwarzschild gravitation core in our Sun at temperature 16 * 106 K. There are now several Teams that are able to achieve this fusion temperature in their special instruments (Tokamak, HL-2M Tokamak, Wendelstein 7-X, NIF, etc.) and to study properties of those formed geons. Thermal geons are with us all the time but they are very deeply hidden in our experiments. We have newly introduced Mareš - Šesták constant as the ratio of geon momentum to heat quantum of geon. The key information to enter into the World of geons was the empirical formula of David Bohm - the very well-known Bohm diffusion. From this formula we have extracted the amplitude, wavelength, frequency, quantum of the geon action, displacement law for geons, etc. It was found that geons are highly sensitive to the magnetic field strength. At a low magnetic field strength, the “inflation of geons” can occur. This effect could explain the Superheating of the Solar corona and the observed Heating of the Earth during two last centuries influenced by the changes in the Earth´s magnetic field. Geon engineering might modify the geon volume through the magnetic field strength. On the other hand, we were stimulated by the works of Mordehai Milgrom and Eric Verlinde and derived the Milgrom-Verlinde constant describing the gravitational field strength leading to the Newtonian gravitational constant on thermodynamic principles. The quantum of the geon momentum might open a new way how to understand gravitational phenomena. Can it be that Nature cleverly inserted geons into our experimental apparatuses and into our very-well known Old Formulae? We want to pass this concept into the hands of Readers of this Journal better educated in the Mathematics, Physics, and Thermodynamics.

scholarly journals Cluster survey of the high-altitude cusp properties: a three-year statistical study

2004 ◽  
Vol 22 (8) ◽  
pp. 3009-3019 ◽  
Author(s):  
B. Lavraud ◽  
A. Fedorov ◽  
E. Budnik ◽  
A. Grigoriev ◽  
P. J. Cargill ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Altitude ◽  
External Boundary ◽  
Plasma Parameters ◽  
Pressure Distributions ◽  
Magnetic Field Model ◽  
Statistical Sense ◽  
Statistical Survey ◽  
Low Magnetic Field ◽  
The Magnetic Field

Abstract. The global characteristics of the high-altitude cusp and its surrounding regions are investigated using a three-year statistical survey based on data obtained by the Cluster spacecraft. The analysis involves an elaborate orbit-sampling methodology that uses a model field and takes into account the actual solar wind conditions and level of geomagnetic activity. The spatial distribution of the magnetic field and various plasma parameters in the vicinity of the low magnetic field exterior cusp are determined and it is found that: 1) The magnetic field distribution shows the presence of an intermediate region between the magnetosheath and the magnetosphere: the exterior cusp, 2) This region is characterized by the presence of dense plasma of magnetosheath origin; a comparison with the Tsyganenko (1996) magnetic field model shows that it is diamagnetic in nature, 3) The spatial distributions show that three distinct boundaries with the lobes, the dayside plasma sheet and the magnetosheath surround the exterior cusp, 4) The external boundary with the magnetosheath has a sharp bulk velocity gradient, as well as a density decrease and temperature increase as one goes from the magnetosheath to the exterior cusp, 5) While the two inner boundaries form a funnel, the external boundary shows no clear indentation, 6) The plasma and magnetic pressure distributions suggest that the exterior cusp is in equilibrium with its surroundings in a statistical sense, and 7) A preliminary analysis of the bulk flow distributions suggests that the exterior cusp is stagnant under northward IMF conditions but convective under southward IMF conditions.

A new furnace for improving thermal demagnetization in paleomagnetism

2020 ◽  
Author(s):  
Huafeng Qin ◽  
Xiang Zhao ◽  
Shuangchi Liu ◽  
Greig Paterson ◽  
Zhaoxia Jiang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Curie Temperature ◽  
High Performance ◽  
Thermal Treatments ◽  
Thermal Demagnetization ◽  
Heating Wire ◽  
Low Magnetic Field ◽  
Detrimental Impact ◽  
The Magnetic Field ◽  
The Ideal

<p>Thermal demagnetization furnaces are routine facilities for paleomagnetic studies. The ideal thermal demagnetizer should maintain “zero” magnetic field during thermal treatments. However, magnetic field noises, including residual magnetic fields of material and induced fields caused by the heating current in the furnace are always present. The key to making high-performance demagnetization furnace is to reduce the magnetic field noises. By combining efficient demagnetization of shielding and a new structure of heating wire, we have developed a new demagnetization furnace with low magnetic field noises. Repeated progressive thermal demagnetization experiments using specimens that were previously completely thermal demagnetized above their Curie temperature were carry out to explore the effects of field within various types of furnace during demagnetization. These experiment confirm that magnetic field noises in the furnace can have an observable and detrimental impact on demagnetization behavior. Comparison between commercial furnaces and our new design show a notable reduction in the impacts of on thermal demagnetization behavior. The new heating element design and procedure for reducing magnetic field noises represent a significant improvement in the design of thermal demagnetizers and allows for extremely weak specimens to be successfully measured.</p>

scholarly journals Impact of Magnetic Field Strengthening on Combustion Performance of Low-Octane Fuel in Two-Stroke Engine

2020 ◽  
Vol 16 (1) ◽  
pp. 57-62
Author(s):  
N. A. Wibowo ◽  
S. M. Utami ◽  
C. A. Riyanto ◽  
A. Setiawan
Keyword(s):  
Magnetic Field ◽  
Near Infrared ◽  
Vibrational Energy ◽  
Field Exposure ◽  
Magnetic Field Exposure ◽  
Combustion Performance ◽  
Molecular Behavior ◽  
Exponential Decrease ◽  
Low Magnetic Field ◽  
The Magnetic Field

The impacts of strengthening magnetic field exposure on combustion performance of low-octane fuel have been examined experimentally. The combustion test was carried out using a 2-stroke 49 cc engine where the fuel was magnetized using a low magnetic field (<2 kG). Moreover, the molecular behavior of magnetized fuel was also characterized through spectrum tests using NIR and UV-Vis spectrophotometers. The result of this study indicates an exponential decrease of magnetized fuel consumption against the strengthening of magnetic field exposure. This exponential decrease of consumption can be related to the Arrhenius principle. In addition, the decrease of oxygen in the exhaust gas along with the strengthening of the magnetic field also confirms the increase of combustion reactions. Meanwhile, the increase of magnetized fuel absorption against ultraviolet and near-infrared lights along with the increase of the magnetic field intensity indicates a bond weakening, accompanied by the increase of molecular vibrational energy.

scholarly journals Exstraordinary and planar Hall effects in thin permalloy films

2021 ◽  
pp. 53-60
Author(s):  
Victoryia I. Halauchyk ◽  
Michail G. Lukashevich
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Film Plane ◽  
Field Direction ◽  
Hall Resistance ◽  
Magnetic Field Direction ◽  
Full Width ◽  
Half Maximum ◽  
Hall Effects ◽  
The Magnetic Field

The Hall resistance hysteresis loops in thin (d = 80 –280 nm) magnetically ordered permalloy films (Ni0.8 Fe0.2) were studied at room temperature at different angles between the film plane and the magnetic field direction (φ = 0 –360°) (extraordinary and ordinary Hall effects), at different angles (θ = 0 – 90°) between the magnetic field direction and the flowing current (planar Hall effect at φ = 0°) in a magnetic field up to B = 1.25 T. The thin films were obtained on sitall dielectric substrate by ion beam sputtering. Sharp peaks of the Hall resistance were observed in the extraordinary and planar Hall effects during the magnetisation reversal of the films due to a change of the magnetisation direction with respect to the sampling current direction. In the extraordinary Hall effect the position and full width at half maximum of a peak is determined by the angle between the magnetic field direction and the film plane. It has been shown that as the direction of the external magnetic field approaches the spontaneous magnetisation direction, both the peak magnetic field position Bp and the full width at half maximum of the peak Δ Bp increase. In the angles range of φ = 0 – 90° Bp and Δ  Bp varies in the magnetic field range from Δ  В ≈ 0.2 to 5.0 mT. A non-monotonic dependence of the planar Hall resistance and its peak position on the angle between the flowing current and the magnetic field direction was detected. It is related to the change of the longitudinal and transverse components the resistance of the magnetically ordered solids by an external magnetic field. The values of the ordinary and extraordinary Hall effects coefficients have been determined: RH0 = 6 ⋅ 10–9 m3/C and RH1 = 3.2 ⋅ 10–8 m3/C, respectively.

scholarly journals QUANTUM CORRECTIONS TO CONDUCTIVITY FOR SEMICONDUCTORS WITH VARIOUS STRUCTURES

2011 ◽  
Vol 25 (14) ◽  
pp. 1915-1929
Author(s):  
S. A. ALAVI ◽  
A. TATAR
Keyword(s):  
Magnetic Field ◽  
Strong Relationship ◽  
Point Of View ◽  
Quantum Corrections ◽  
Theoretical Point ◽  
Quantum Well Structures ◽  
Temperature Ranges ◽  
Heavily Doped ◽  
Low Magnetic Field ◽  
The Magnetic Field

We study the magnetic field dependences of the conductivity in heavily doped, strongly disordered 2D quantum well structures within wide conductivity and temperature ranges. We show that the exact analytical expression derived in our previous paper [S. A. Alavi and S. Rouhani, Phys. Lett. A320, 327 (2004)], is in better agreement with the existing equation, i.e., Hikami et al. expression [ Prog. Theor. Phys.63, 707 (1980)] and Littman and Schmid expression [J. Low Temp. Phys.69, 131 (1987)], with the experimental data even in low magnetic field for which the diffusion approximation is valid. On the other hand from theoretical point of view we observe that our equation is also rich because it establishes a strong relationship between quantum corrections to the conductivity and the quantum symmetry Suq(2). It is shown that the quantum corrections to the conductivity is the trace of Green function made by a generator of Suq(2) algebra. Using this fact we show that the quantum corrections to the conductivity can be expressed as a sum of an infinite number of Feynman diagrams.

MAGNETIC PROPERTY AND CRITICAL CURRENT OF BiSrCaCuO SYSTEM UNDER LOW MAGNETIC FIELD

1989 ◽  
Vol 03 (06) ◽  
pp. 505-508
Author(s):  
L.Z. CAO ◽  
Y. YUE ◽  
J. WANG ◽  
S.D. MAO ◽  
H.B. LIU ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Property ◽  
Critical Current ◽  
Critical Field ◽  
Current Density ◽  
Pinning Force ◽  
Earth’S Magnetic Field ◽  
Earth's Magnetic Field ◽  
Low Magnetic Field ◽  
The Magnetic Field

The low critical field H c1 is determined by a.c.χ versus H and M versus H. For a sample of BiSrCaCuO with T c (0)=89 K , H c1 is equal to 17.5 Oe at 77 K. Measurement of the critical current Jc under low magnetic field shows that there is a peak on J c -H curve at about 1 Oe due to the existence of the earth’s magnetic field and the current density is very small in the BiSrCaCuO system and J c is nearly zero when the magnetic field reaches 150 Oe. It is suggested that the pinning force is very weak in this material.

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.

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