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A novel strategy is proposed for the coupling of field and circuit equations when modeling power devices in the low-frequency regime. The resulting systems of differential-algebraic equations have a particular geometric structure which…

Numerical Analysis · Mathematics 2024-04-25 Herbert Egger , Idoia Cortes Garcia , Vsevolod Shashkov , Michael Wiesheu

We consider an exact magnetic flow on the tangent bundle of a closed surface. We prove that for almost every energy level $\kappa$ below the Ma\~n\'e critical value of the universal cover there are infinitely many periodic orbits with…

Dynamical Systems · Mathematics 2017-01-30 Alberto Abbondandolo , Leonardo Macarini , Marco Mazzucchelli , Gabriel P. Paternain

Magnetization reversal in permanent magnets occurs by the nucleation and expansion of reversed domains. Micromagnetic theory offers the possibility to localize the spots within the complex structure of the magnet where magnetization…

Materials Science · Physics 2018-05-25 J. Fischbacher , A. Kovacs , L. Exl J. Kühnel , E. Mehofer , H. Sepehri-Amin , T. Ohkubo , K. Hono , T. Schrefl

State of the art numerical models of the Geodynamo are still performed in a parameter regime extremely remote from the values relevant to the physics of the Earth's core. In order to establish a connection between dynamo modeling and the…

Geophysics · Physics 2015-06-18 Ludivine Oruba , Emmanuel Dormy

Quantum electrodynamics (QED) becomes nonlinear when the magnetic field strength surpasses the critical Schwinger limit $B_Q \approx 4.41\cdot 10^{13}$ G. This limit is surpassed, for example, in the magnetospheres of a specific class of…

High Energy Physics - Phenomenology · Physics 2026-03-30 Olavi Kiuru

We derive a closed-form expression of the magnetic field of a finite-size current sheet and use it to calculate the field of permanent magnets, which are modeled through their surface current densities. We illustrate the method by…

Applied Physics · Physics 2022-11-02 Volker Ziemann

We shall here discuss a characterization of geodesics trajectories. We shall show that the action of the gravitational field on mass particles can be essentially identified with the force that cannot be absolutely eliminated. This leads to…

General Relativity and Quantum Cosmology · Physics 2011-06-21 L. Fatibene , M. Francaviglia , G. Magnano

The geometric concept of geodesic completeness depends on the choice of the metric field or "metric frame". We develop a frame-invariant concept of "generalised geodesic completeness" or "time completeness". It is based on the notion of…

General Relativity and Quantum Cosmology · Physics 2022-10-21 V. A. Rubakov , C. Wetterich

One of the most intriguing features of Earth's axial magnetic dipole field, well-known from the geological record, is its occasional and unpredictable reversal of polarity. Understanding the phenomenon is rendered very difficult by the…

Geophysics · Physics 2019-01-02 Christian R. Scullard , Bruce A. Buffett

We develop a formulation of the strong deflection limit for the scattering of particles following timelike geodesics in asymptotically flat, static, and spherically symmetric spacetimes. For fixed specific energy, as the angular momentum…

General Relativity and Quantum Cosmology · Physics 2026-03-11 Takahisa Igata , Yohsuke Takamori

The time-varying geomagnetic field is a superposition of contributions from multiple internal and external current systems. A major source of geomagnetic variations at periods less than a few years are current systems external to the solid…

Space Physics · Physics 2025-03-11 Jingtao Min , Alexander Grayver

Multiscale phenomena which include several processes occuring simultaneously at different length scales and exchanging energy with each other, are widespread in magnetism. These phenomena often govern the magnetization reversal dynamics,…

Materials Science · Physics 2009-10-31 V. V. Dobrovitski , M. I. Katsnelson , B. N. Harmon

We derive a gyrokinetic formalism which is very generally valid: the ordering allows both large inhomogeneities in plasma flow and magnetic field at long wavelength, like typical drift-kinetic theories, as well as fluctuations at the…

Plasma Physics · Physics 2016-09-21 Ben F McMillan , Amil Sharma

Large scale dynamo-generated fields are a combination of interlocked poloidal and toroidal fields. Such fields possess magnetic helicity that needs to be regenerated and destroyed during each cycle. A number of numerical experiments now…

Astrophysics · Physics 2009-11-13 Axel Brandenburg

The switching of magnetic layers is studied under the action of a spin current in a ferromagnetic metal/non-magnetic metal/ferromagnetic metal spin valve. We find that the main contribution to the switching comes from the non-equilibrium…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 C. Heide , P. E. Zilberman , R. J. Elliott

The tunneling splitting of the energy levels of a ferromagnetic particle in the presence of an applied magnetic field - previously derived only for the ground state with the path integral method - is obtained in a simple way from…

Condensed Matter · Physics 2019-08-17 J. -Q. Liang , H. J. W. Mueller-Kirsten , A. V. Shurgaia , F. Zimmerschied

We introduce microscopic polarization and magnetization fields at each site of an extended system, as well as free charge and current density fields associated with charge movement from site to site, by employing a lattice gauge approach…

Mesoscale and Nanoscale Physics · Physics 2019-06-21 Perry T. Mahon , Rodrigo A. Muniz , J. E. Sipe

The purpose of this paper is to formulate a kinetic theory describing transport properties of electrons in a uniform magnetic field of arbitrary magnitude. Exposing an electronic system to a constant magnetic field quenches its energy bands…

Mesoscale and Nanoscale Physics · Physics 2025-09-09 Kitinan Pongsangangan

Straining of magnetic fields by large-scale shear flow, generally assumed to lead to intensification and generation of small scales, is re-examined in light of the persistent observation of large-scale magnetic fields in astrophysics. It is…

Plasma Physics · Physics 2022-07-20 B. Tripathi , A. E. Fraser , P. W. Terry , E. G. Zweibel , M. J. Pueschel

Magnetic and kinetic energy in ideal incompressible MHD are not global invariants and, therefore, it had been justified to discuss only the cascade of their sum, total energy. We provide a physical argument based on scale-locality of the…

Solar and Stellar Astrophysics · Physics 2019-02-26 Xin Bian , Hussein Aluie