MAGNETORESISTANCE AND FIELD DEPENDENCE OF THE HALL EFFECT IN INDIUM ANTIMONIDE

1958 ◽  
Vol 36 (5) ◽  
pp. 527-538 ◽  
Author(s):  
Gaston Fischer ◽  
D. K. C. MacDonald
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Field Dependence ◽  
Indium Antimonide ◽  
Charge Carriers ◽  
Band Theory ◽  
Hall Effect Measurements ◽  
A Charge ◽  
The Magnetic Field

Magnetoresistance and Hall-effect measurements in InSb are described. This semiconductor has charge carriers with sufficiently long mean free paths, l, that it is possible, even at room temperature and with available magnetic fields, to obtain l/r values considerably greater than unity, r being the orbital radius of a charge carrier moving in the applied magnetic field. The classical two-band theory has been found to account rather well for the results up to the highest magnetic fields employed. A review of the underlying assumptions of this theory is presented, and simple formulae are derived which allow the concentrations and mobilities of both types of carriers to be calculated from the magnetic field dependence of the resistivity, ρH, and of the Hall-constant, AH. The parameter Λ ≡ [(AH−A0)/A0]/[(ρH−ρ0)/ρ0] provides a useful means to check the consistency of the theory and can give some indication of the variation of the mobilities with the magnetic field.

Magnetostrictive Self-Diagnosing Smart Bolts

2014 ◽  
Author(s):  
Vladislav Sevostianov
Keyword(s):  
Magnetic Field ◽  
Plastic Deformation ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Stress Level ◽  
Experimental Validation ◽  
Rock Bolts ◽  
Three Point Bending ◽  
Bending Loading ◽  
The Magnetic Field

The paper presents the concept of self-diagnosing smart bolts and its experimental validation. In the present research such bolts are designed, built, and experimentally tested. As a key element of the design, wires of Galfenol (alloy of iron and gallium) are used. This material shows magnetostrictive properties, and, at the same time, is sufficiently ductile to follow typical deformation of rock bolts, and is economically affordable. Two types of Galfenol were used: Ga10Fe90 and Ga17Fe83. The wires have been installed in bolts using two designs — in a drilled central hole or in a cut along the side — and the bolts were tested for generation of the magnetic field under three-point bending loading. To measure the magnetic field in the process of deformation, a magnetometer that utilizes the GMR effect was designed, built, and compared with one utilizing the Hall effect. It is shown that (1) magnetic field generated by deformation of the smart bolts at the stress level of plastic deformation is sufficient to be noticed by the proposed magnetometer; however, the magnetometer using Hall effect is insufficient; (2) Ga10Fe90 produces higher magnetic fields than Ga17Fe83; (3) the magnetic field in plastically bended bolts is relatively stable with time.

scholarly journals Magnetic Field Evolution in Neutron Star Crusts: Beyond the Hall Effect

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 130
Author(s):  
Konstantinos N. Gourgouliatos ◽  
Davide De Grandis ◽  
Andrei Igoshev
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Hall Effect ◽  
Thermal Emission ◽  
Ohmic Dissipation ◽  
Field Evolution ◽  
The Universe ◽  
The Magnetic Field ◽  
Maxwell Stresses

Neutron stars host the strongest magnetic fields that we know of in the Universe. Their magnetic fields are the main means of generating their radiation, either magnetospheric or through the crust. Moreover, the evolution of the magnetic field has been intimately related to explosive events of magnetars, which host strong magnetic fields, and their persistent thermal emission. The evolution of the magnetic field in the crusts of neutron stars has been described within the framework of the Hall effect and Ohmic dissipation. Yet, this description is limited by the fact that the Maxwell stresses exerted on the crusts of strongly magnetised neutron stars may lead to failure and temperature variations. In the former case, a failed crust does not completely fulfil the necessary conditions for the Hall effect. In the latter, the variations of temperature are strongly related to the magnetic field evolution. Finally, sharp gradients of the star’s temperature may activate battery terms and alter the magnetic field structure, especially in weakly magnetised neutron stars. In this review, we discuss the recent progress made on these effects. We argue that these phenomena are likely to provide novel insight into our understanding of neutron stars and their observable properties.

Galvanomagnetic and thermomagnetic phenomena

2004 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Magnetic Field ◽  
Heat Flow ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Electric Current ◽  
Lorentz Force ◽  
Electrical Resistance ◽  
Magnetic Flux Density ◽  
Wide Range ◽  
The Magnetic Field

The Lorentz force that a magnetic field exerts on a moving charge carrier is perpendicular to the direction of motion and to the magnetic field. Since both electric and thermal currents are carried by mobile electrons and ions, a wide range of galvanomagnetic and thermomagnetic effects result. The effects that occur in an isotropic polycrystalline metal are illustrated in Fig. 20.1. As to be expected, many more cross-coupled effects occur in less symmetric solids. The galvanomagnetic experiments involve electric field, electric current, and magnetic field as variables. The Hall Effect, transverse magnetoresistance, and longitudinal magnetoresistance all describe the effects of magnetic fields on electrical resistance. Analogous experiments on thermal conductivity are referred to as thermomagnetic effects. In this case the variables are heat flow, temperature gradient, and magnetic field. The Righi–Leduc Effect is the thermal Hall Effect in which magnetic fields deflect heat flow rather than electric current. The transverse thermal magnetoresistance (the Maggi–Righi–Leduc Effect) and the longitudinal thermal magnetoresistance are analogous to the two galvanomagnetic magnetoresistance effects. Additional interaction phenomena related to the thermoelectric and piezoresistance effects will be discussed in the next two chapters. In tensor form Ohm’s Law is . . .Ei = ρijJj , . . . where Ei is electrical field, Jj electric current density, and ρij the electrical resistivity in Ωm. In describing the effect of magnetic field on electrical resistance, we expand the resistivity in a power series in magnetic flux density B. B is used rather than the magnetic field H because the Lorentz force acting on the charge carriers depends on B not H.

scholarly journals Fluctuation Effects of Magnetohydrodynamic Micro-Vortices on Odd Chirality in Magnetoelectrolysis

2020 ◽  
Vol 6 (3) ◽  
pp. 43
Author(s):  
Iwao Mogi ◽  
Ryoichi Aogaki ◽  
Kohki Takahashi
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Dependence ◽  
Magnetic Field Dependence ◽  
Ionic Currents ◽  
Copper Films ◽  
Field Polarity ◽  
Vortex Model ◽  
Self Organized ◽  
The Magnetic Field

The magnetic field dependence of chiral surface formation was investigated in magnetoelectrodeposition (MED) and magnetoelectrochemical etching (MEE) of copper films. The MED and MEE was conducted in magnetic fields of up to 5 T, which were parallel or antiparallel to the ionic currents. The MED films prepared in high magnetic fields of 5 and 3 T exhibited odd chirality for magnetic field polarity, as expected on the basis of the magnetohydrodynamic (MHD) vortex model. However, the films prepared in the lower fields of 2.5 and 2 T exhibited breaking of odd chirality. Similar magnetic field dependence was observed in the surface chirality of MEE films. These results imply that the fluctuation in the self-organized state of micro-MHD vortices is responsible for the breaking of odd chirality.

INFLUENCE OF MAGNETIC FIELDS ON THE INTRINSIC SPIN HALL EFFECT IN TWO-DIMENSIONAL SYSTEMS

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2566-2572 ◽  
Author(s):  
O. E. RAICHEV
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Berry Phase ◽  
Zeeman Splitting ◽  
Hall Conductivity ◽  
Spin Hall Effect ◽  
Two Dimensional ◽  
The Magnetic Field ◽  
Spin Hall Conductivity

The influence of magnetic fields on the electron spin in solids involves two basic mechanisms. First, any magnetic field introduces the Zeeman splitting of electron states, thereby modifying spin precession. Second, since the magnetic field affects the electron motion in the plane perpendicular to the field, the spin dynamics is also modified, owing to the spin-orbit interaction. The theory predicts, as a consequence of this influence, unusual properties of the intrinsic spin-Hall effect in two-dimensional systems in the presence of magnetic fields. This paper describes non-monotonic dependence of the spin-Hall conductivity on the magnetic field and its enhancement in the case of weak disorder, as well as multiple jumps of the spin-Hall conductivity owing to the topological transitions (abrupt changes of the Berry phase) induced by the parallel magnetic field.

scholarly journals Pion decay in magnetic fields

2018 ◽  
Vol 175 ◽  
pp. 13005 ◽  
Author(s):  
Gunnar S. Bali ◽  
Bastian B. Brandt ◽  
Gergely Endrődi ◽  
Benjamin Gläße
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Decay Rate ◽  
Field Dependence ◽  
Magnetic Field Dependence ◽  
Charged Pion ◽  
Pion Decay ◽  
Total Decay Rate ◽  
Decay Constants ◽  
The Magnetic Field

The leptonic decay of the charged pion in the presence of background magnetic fields is investigated using quenched Wilson fermions. It is demonstrated that the magnetic field opens up a new channel for this decay. The magnetic field-dependence of the decay constants for both the ordinary and the new channel is determined. Using these inputs from QCD, we calculate the total decay rate perturbatively.

scholarly journals Hall-Effect Sensor Technique for No Induced Voltage in AC Magnetic Field Measurements Without Current Spinning

2021 ◽  
Author(s):  
Anand Lalwani ◽  
Ananth Saran Yalamarthy ◽  
Debbie Senesky ◽  
Maximillian Holliday ◽  
Hannah Alpert
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Induced Voltage ◽  
Field Frequency ◽  
Magnetic Field Frequency ◽  
Ac Magnetic Field ◽  
Hall Effect Sensor ◽  
Offset Voltage ◽  
The Magnetic Field

Accurately sensing AC magnetic field signatures poses a series of challenges to commonly used Hall-effect sensors. In particular, induced voltage and lack of high-frequency spinning methods are bottlenecks in the measurement of AC magnetic fields. We describe a magnetic field measurement technique that can be implemented in two ways: 1) the current driving the Hall-effect sensor is oscillating at the same frequency as the magnetic field, and the signal is measured at the second harmonic of the magnetic field frequency, and 2) the frequency of the driving current is preset, and the measured frequency is the magnetic field frequency plus the frequency of the current. This method has potential advantages over traditional means of measuring AC magnetic fields used in power systems (e.g., motors, inverters), as it can reduce the components needed (subsequently reducing the overall cost and size) and is not frequency bandwidth limited by current spinning. The sensing technique produces no induced voltage and results in a low offset, thus preserving accuracy and precision in measurements. Experimentally, we have shown offset voltage values between 8 and 27 μT at frequencies ranging from 100 Hz to 1 kHz, validating the potential of this technique in both cases

scholarly journals Hall-Effect Sensor Technique for No Induced Voltage in AC Magnetic Field Measurements Without Current Spinning

2021 ◽  
Author(s):  
Anand Lalwani ◽  
Ananth Saran Yalamarthy ◽  
Debbie Senesky ◽  
Maximillian Holliday ◽  
Hannah Alpert
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Induced Voltage ◽  
Field Frequency ◽  
Magnetic Field Frequency ◽  
Ac Magnetic Field ◽  
Hall Effect Sensor ◽  
Offset Voltage ◽  
The Magnetic Field

Accurately sensing AC magnetic field signatures poses a series of challenges to commonly used Hall-effect sensors. In particular, induced voltage and lack of high-frequency spinning methods are bottlenecks in the measurement of AC magnetic fields. We describe a magnetic field measurement technique that can be implemented in two ways: 1) the current driving the Hall-effect sensor is oscillating at the same frequency as the magnetic field, and the signal is measured at the second harmonic of the magnetic field frequency, and 2) the frequency of the driving current is preset, and the measured frequency is the magnetic field frequency plus the frequency of the current. This method has potential advantages over traditional means of measuring AC magnetic fields used in power systems (e.g., motors, inverters), as it can reduce the components needed (subsequently reducing the overall cost and size) and is not frequency bandwidth limited by current spinning. The sensing technique produces no induced voltage and results in a low offset, thus preserving accuracy and precision in measurements. Experimentally, we have shown offset voltage values between 8 and 27 μT at frequencies ranging from 100 Hz to 1 kHz, validating the potential of this technique in both cases

Notizen: The Effect of Carrier Concentration on Microwave Emission from n-Type Indium Antimonide

1970 ◽  
Vol 25 (10) ◽  
pp. 1517-1518 ◽  
Author(s):  
W. A. Porter ◽  
D. K. Ferry
Keyword(s):  
Magnetic Field ◽  
Carrier Concentration ◽  
Field Dependence ◽  
Electric Fields ◽  
Indium Antimonide ◽  
Magnetic Field Dependence ◽  
Microwave Emission ◽  
The Magnetic Field

The effect of carrier concentration on the threshold for microwave emission from InSb was determined. Threshold electric fields are lower for higher concentrations and the magnetic field dependence is reduced.

Influences on Occurrence of Magnetism During Cutting Processes

2011 ◽  
Vol 5 (3) ◽  
pp. 294-299
Author(s):  
Dirk Bähre ◽  
◽  
Kirsten Trapp ◽  
Ralf Tschuncky ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Ferromagnetic Materials ◽  
Material Structure ◽  
Time Dependency ◽  
Technological Parameters ◽  
Cutting Processes ◽  
The Impact ◽  
The Magnetic Field

Workpieces from ferromagnetic materials influenced by machining can build magnetic fields, which can cause problems in production or application. One of the assumed causes of magnetism occurring in cutting processes is the change in the material structure due to the impact of the tool. To study these influences, milling tests are carried out. The magnetic field is measured by means of sensors functioning on the basis of the Hall effect. The coherences between geometry, kinematics, technological parameters, time dependency, and the magnetisation characteristics of the workpiece are considered.

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