scholarly journals RIGOROUS SEMICLASSICAL RESULTS FOR THE MAGNETIC RESPONSE OF AN ELECTRON GAS

2001 ◽  
Vol 13 (09) ◽  
pp. 1055-1073 ◽  
Author(s):  
MONIQUE COMBESCURE ◽  
DIDIER ROBERT
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Thermal Equilibrium ◽  
Electron Gas ◽  
Point Of View ◽  
Magnetic Response ◽  
Planck Constant ◽  
Confining Potential ◽  
Electronic Motion ◽  
Arbitrary Dimensions

Consider a free electron gas in a confining potential and a magnetic field in arbitrary dimensions. If this gas is in thermal equilibrium with a reservoir at temperature T>0, one can study its orbital magnetic response (omitting the spin). One defines a conveniently "smeared out" magnetization M, and the corresponding magnetic susceptibility χ, which will be analyzed from a semiclassical point of view, namely when ℏ (the Planck constant) is small compared to classical actions characterizing the system. Then various regimes of temperature T are studied where M and χ can be obtained in the form of suitable asymptotic ℏ-expansions. In particular when T is of the order of ℏ, oscillations "à la de Haas-van Alphen" appear, that can be linked to the classical periodic orbits of the electronic motion.

scholarly journals Vortex guide under a Lorentz force

2020 ◽  
pp. 101-106
Author(s):  
C. A. Aguirre ◽  
Q. Martins ◽  
Jose Barba
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
External Magnetic Field ◽  
Lorentz Force ◽  
Vortex State ◽  
Cooper Pairs ◽  
Magnetic Response ◽  
External Current ◽  
Critical Temperatures ◽  
Ginzburg Landau

In the present work we studied the effect of the nature of the contacts, by which a weak external current is applied, in an anisotropic superconducting rectangle, on the magnetization, magnetic susceptibility, density of the Cooper pairs and  (magnetic field for which the first vortices entry on the sample). The contacts are simulates by the  parameter, and the anisotropy is present in sections with different critical temperatures modeling for  function, both in the Ginzburg-Landau formalis. Also, the sample is embebbed in an external magnetic field . We established how the nature of the contacts and the presence of a weak Lorentz Force, influence the magnetic response and the vortex state of the sample.

scholarly journals The AC Multi-Harmonic Magnetic Susceptibility Measurement Setup at the LNF-INFN

2014 ◽  
Vol 568-570 ◽  
pp. 82-89 ◽  
Author(s):  
Sheng Hao Wang ◽  
Augusto Marcelli ◽  
Daniele Di Gioacchino ◽  
Zi Yu Wu
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Materials Science ◽  
Superconducting Magnet ◽  
Magnetic Response ◽  
Ac Magnetic Susceptibility ◽  
Frequency Range ◽  
Control Data ◽  
Dc Magnetic Field ◽  
User Friendly

The AC magnetic susceptibility is a fundamental method in materials science, which allows to probe the dynamic magnetic response of magnetic materials and superconductors. The LAMPS laboratory at the Laboratori Nazionali di Frascati of the INFN hosts an AC multi-harmonic magnetometer that allows performing experiments with an AC magnetic field ranging from 0.1 to 20 Gauss and in the frequency range from 17 to 2070 Hz. A DC magnetic field from 0 to 8 T produced by a superconducting magnet can be applied, while data may be collected in the temperature range 4.2-300 K using a liquid He cryostat under different temperature cycles setups. The first seven AC magnetic multi-harmonic susceptibility components can be measured with a magnetic sensitivity of 1x10-6 emu and a temperature precision of 0.01 K. Here we will describe in detail about schematic of the magnetometer, special attention will be dedicated to the instruments control, data acquisition framework and the user-friendly LabVIEW-based software platform.

The magnetic susceptibility of an electron gas

1962 ◽  
Vol 265 (1321) ◽  
pp. 215-228 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Electron Gas ◽  
Quantum Mechanical ◽  
Uniform Field ◽  
Zero Temperature ◽  
Coupling Constant ◽  
First Order ◽  
The Magnetic Field ◽  
Density Expansion

The cluster expansion of the quantum-mechanical grand partition function is obtained for a gas of interacting charged particles in a uniform magnetic field. The magnetic field is conveniently included by using a Green function for a charged particle in a uniform field. The theory is applied to calculate the magnetic susceptibility of an electron gas for small magnetic fields. For Boltzmann statistics the equation of state is unaltered to the DebyeHuckel approximation and the field only enters into the quantum-mechanical corrections to this equation. The first terms in a low-density expansion of the susceptibility are obtained. For Fermi-Dirac statistics an exact high-density expansion of the susceptibility to first order in the coupling constant is obtained at zero temperature. The first-order exchange energy is divergent but this divergence is removed by including the ring diagrams.

An Augmented Iteratively Re-weighted and Refined Least Squares Method for lp Minimization Problem in Inverse Modeling of Potential Field Magnetic Data

2020 ◽  
Vol 1 (3) ◽  
Author(s):  
Maysam Abedi
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Least Squares ◽  
Minimization Problem ◽  
Potential Field ◽  
Field Data ◽  
Least Squares Method ◽  
Porphyry Copper ◽  
Magnetic Data ◽  
Magnetic Field Data

The presented work examines application of an Augmented Iteratively Re-weighted and Refined Least Squares method (AIRRLS) to construct a 3D magnetic susceptibility property from potential field magnetic anomalies. This algorithm replaces an lp minimization problem by a sequence of weighted linear systems in which the retrieved magnetic susceptibility model is successively converged to an optimum solution, while the regularization parameter is the stopping iteration numbers. To avoid the natural tendency of causative magnetic sources to concentrate at shallow depth, a prior depth weighting function is incorporated in the original formulation of the objective function. The speed of lp minimization problem is increased by inserting a pre-conditioner conjugate gradient method (PCCG) to solve the central system of equation in cases of large scale magnetic field data. It is assumed that there is no remanent magnetization since this study focuses on inversion of a geological structure with low magnetic susceptibility property. The method is applied on a multi-source noise-corrupted synthetic magnetic field data to demonstrate its suitability for 3D inversion, and then is applied to a real data pertaining to a geologically plausible porphyry copper unit.  The real case study located in  Semnan province of  Iran  consists  of  an arc-shaped  porphyry  andesite  covered  by  sedimentary  units  which  may  have  potential  of  mineral  occurrences, especially  porphyry copper. It is demonstrated that such structure extends down at depth, and consequently exploratory drilling is highly recommended for acquiring more pieces of information about its potential for ore-bearing mineralization.

ABOUT UNIFORMITY OF THE PHENOMENOLOGY AND THE MATHEMATICAL DESCRIPTION OF SO-CALLED « JOINED» ACTION OF HAZARDS AND COMBINED TOXICITY (ON THE EXAMPLE OF A COMBIBATION OF THE FLUORIDE AND THE STATIC MAGNETIC FIELD)

2016 ◽  
pp. 13-20
Author(s):  
B. A. Katsnelson ◽  
M. P. Sutunkova ◽  
N. A. Tsepilov ◽  
V. G. Panov ◽  
A. N. Varaksin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Point Of View ◽  
Whole Body ◽  
Surface Model ◽  
Combined Toxicity ◽  
Fluoride Solution ◽  
Adverse Action ◽  
Biochemical Indices ◽  
And Control

Sodium fluoride solution was injected i.p. to three groups of rats at a dose equivalent to 0.1 LD50 three times a week up to 18 injections. Two out of these groups and two out of three groups were sham-injected with normal saline and were exposed to the whole body impact of a 25 mT static magnetic field (SMF) for 2 or 4 hr a day, 5 times a week. Following the exposure, various functional and biochemical indices were evaluated along with histological examination and morphometric measurements of the femur in the differently exposed and control rats. The mathematical analysis of the combined effects of the SMF and fluoride based on the a response surface model demonstrated that, in full correspondence with what we had previously found for the combined toxicity of different chemicals, the combined adverse action of a chemical plus a physical agent was characterized by a tipological diversity depending not only on particular effects these types were assessed for but on the dose and effect levels as well. From this point of view, the indices for which at least one statistically significant effect was observed could be classified as identifying (I) mainly single-factor action; (II) additive unidirectional action; (III) synergism (superadditive unidirectional action); (IV) antagonism, including both subadditive unidirectional action and all variants of contradirectional action.

scholarly journals No-z Model for Magnetic Fields of Different Astrophysical Objects and Stability of the Solutions

Data ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Evgeny Mikhailov ◽  
Daniela Boneva ◽  
Maria Pashentseva
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Point Of View ◽  
Accretion Discs ◽  
Wide Range ◽  
Astrophysical Objects ◽  
Alpha Effect ◽  
The Stability ◽  
The Magnetic Field

A wide range of astrophysical objects, such as the Sun, galaxies, stars, planets, accretion discs etc., have large-scale magnetic fields. Their generation is often based on the dynamo mechanism, which is connected with joint action of the alpha-effect and differential rotation. They compete with the turbulent diffusion. If the dynamo is intensive enough, the magnetic field grows, else it decays. The magnetic field evolution is described by Steenbeck—Krause—Raedler equations, which are quite difficult to be solved. So, for different objects, specific two-dimensional models are used. As for thin discs (this shape corresponds to galaxies and accretion discs), usually, no-z approximation is used. Some of the partial derivatives are changed by the algebraic expressions, and the solenoidality condition is taken into account as well. The field generation is restricted by the equipartition value and saturates if the field becomes comparable with it. From the point of view of mathematical physics, they can be characterized as stable points of the equations. The field can come to these values monotonously or have oscillations. It depends on the type of the stability of these points, whether it is a node or focus. Here, we study the stability of such points and give examples for astrophysical applications.

Sign in / Sign up

Export Citation Format

Share Document