Vaulting and Displacement of Pole-Covered 180°-Domain Walls

1974 ◽  
Vol 29 (3) ◽  
pp. 457-461
Author(s):  
H. Markert
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Domain Walls ◽  
Magnetic Surface ◽  
Repulsive Interaction ◽  
Zero Approximation ◽  
Linear Barrier

A zero approximation has been given of the normalized vaulting amplitudes of 180°-domain walls which are assumed to be vaulted between repulsive interaction lines if equilibrium has taken place between an external magnetic field and the counteracting forces resulting from the stray fields of the vaulting-induced free magnetic surface poles. Calculations have been carried out for two cases: cylindrical vaulting between linear barrier lines and pillow-shaped vaulting between isolated interaction points building up a tridimensional lattice of hindering points

Notizen: Reactivation of Mechanical Aftereffect of Iron Single Crystals by Discontinuous Change of External Magnetic Field

1972 ◽  
Vol 27 (2) ◽  
pp. 371-372 ◽  
Author(s):  
H. Markert
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystals ◽  
Domain Walls ◽  
Repulsive Interaction ◽  
Discontinuous Change ◽  
Interaction Forces

AbstractFirst experiments on iron single crystals are outlined demonstrating that the mechanical aftereffect can be reactivated remarkably by discontinuous changes in superimposed magnetic fields. As magnetostrictive effects not only are very much smaller but can also be separated experimentally, it appears to be necessary to interpret the observed phenomena by interactions between domain walls and dislocations having mutual orientations suitable to enable reactivation of disclocation glide caused by the repulsive interaction forces of the domain walls.

scholarly journals The Microstructural Model of the Ferromagnetic Material Behavior in an External Magnetic Field

2021 ◽  
Vol 7 (1) ◽  
pp. 7
Author(s):  
Anatoli A. Rogovoy ◽  
Oleg V. Stolbov ◽  
Olga S. Stolbova
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Domain Walls ◽  
Magnetic Energy ◽  
Spontaneous Magnetization ◽  
Magnetization Vector ◽  
Ferromagnetic Material ◽  
Extremum Problem ◽  
Material Behavior ◽  
Anisotropy Axis

In this paper, the behavior of a ferromagnetic material is considered in the framework of microstructural modeling. The equations describing the behavior of such material in the magnetic field, are constructed based on minimization of total magnetic energy with account of limitations imposed on the spontaneous magnetization vector and scalar magnetic potential. This conditional extremum problem is reduced to the unconditional extremum problem using the Lagrange multiplier. A variational (weak) formulation is written down and linearization of the obtained equations is carried out. Based on the derived relations a solution of a two-dimensional problem of magnetization of a unit cell (a grain of a polycrystal or a single crystal of a ferromagnetic material) is developed using the finite element method. The appearance of domain walls is demonstrated, their thickness is determined, and the history of their movement and collision is described. The graphs of distributions of the magnetization vector in domains and in domain walls in the external magnetic field directed at different angles to the anisotropy axis are constructed and the magnetization curves for a macrospecimen are plotted. The results obtained in the present paper (the thickness of the domain wall, the formation of a 360-degree wall) are in agreement with the ones available in the current literature.

scholarly journals Magnetization Reversal in Ferromagnetic Nanorings of Fourfold Symmetries

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Andrea Ehrmann ◽  
Tomasz Blachowicz
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetization Reversal ◽  
Domain Walls ◽  
Memory Devices ◽  
Micromagnetic Simulations ◽  
Stable Intermediate ◽  
Intermediate States ◽  
The Stability ◽  
Ferromagnetic Nanorings

Magnetic nanoparticles offer a broad spectrum of magnetization reversal processes and respective magnetic states, such as onion, horseshoe, or vortex states as well as various states including domain walls. These states can be correlated with stable intermediate states at remanence, enabling new quaternary memory devices storing two bits in one particle. The stability of these intermediated states was tested with respect to shape modifications, variations in the anisotropy axes, and rotations and fluctuations of the external magnetic field. In our micromagnetic simulations, 6 different stable intermediate states were observed at vanishing magnetic field in addition to the remanence state. The angular region of approx. 5°–12° between nanoring and external magnetic field was identified as being most stable with respect to all modifications, with an onion state as technologically best accessible intermediate state to create quaternary memory devices.

scholarly journals The Dynamics of Domain Wall Motion in Spintronics

2020 ◽  
Vol 6 (3) ◽  
pp. 40
Author(s):  
Diego Bisero
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
External Magnetic Field ◽  
Domain Wall ◽  
Effective Mass ◽  
General Equation ◽  
Wall Motion ◽  
Domain Walls ◽  
Domain Wall Motion ◽  
Magnetic Thin Film

A general equation describing the motion of domain walls in a magnetic thin film in the presence of an external magnetic field has been reported in this paper. The equation includes all the contributions from the effects of domain wall inertia, damping and stiffness. The effective mass of the domain wall, the effects of both the interaction of the DW with the imperfections in the material and damping have been calculated.

Micromagnetic Simulation of CoFe Magnetic Nanorings: Switching Behavior in External Magnetic Field

2013 ◽  
Vol 710 ◽  
pp. 80-84 ◽  
Author(s):  
Zhen Gang Guo ◽  
Li Qing Pan ◽  
Hong Mei Qiu ◽  
M. Yasir Rafique ◽  
Shuai Zeng
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetization Reversal ◽  
Domain Walls ◽  
Vortex State ◽  
Switching Behavior ◽  
Switching Field ◽  
Reversal Process ◽  
Magnetic States ◽  
Magnetization Processes

The magnetization reversal processes of magnetic nanorings (Co50Fe50) with different geometric shapes are investigated. In addition to the expected onion and vortex magnetization states, other metastable states are observed in the magnetization processes. We anatomize the formation and transition of magnetic states, and the propagation and annihilation of domain walls in the reversal process through the dynamic picture. Phase diagrams for the magnetization switching behavior depending on the geometric parameters are presented. The simulation shows that the vortex state is stabilized in thick and narrow rings. The switching field from vortex to onion states turns out to increase with thickness and decrease with width and diameter.

Direct Observation of Reverse Magnetic Domain and Magnetic Domain Wall Motion in Nd-Fe-B Magnet at High Temperature by Lorentz Microscop

MRS Advances ◽  
2016 ◽  
Vol 1 (3) ◽  
pp. 241-246 ◽  
Author(s):  
Toshimasa Suzuki ◽  
Koichi Kawahara ◽  
Masaya Suzuki ◽  
Kenta Takagi ◽  
Kimihiro Ozaki
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Domain Wall ◽  
Wall Motion ◽  
Domain Walls ◽  
Magnetic Domain ◽  
Domain Wall Motion ◽  
Thin Foil ◽  
Magnetic Domain Wall

ABSTRACTWe conducted the in-situ observations of the magnetic domain structure change in Nd-Fe-B magnets at high temperature by transmission electron microscopy (TEM) / Lorentz microscopy with applying an external magnetic field. Prior to observation, a thin foil was magnetized by an external magnetic field of 2.0 T to almost saturation, then the magnetic domain structures were observed by the Fresnel mode with in-situ heating. At 225°C, reverse magnetic domains were found to generate in the thin foil sample without applying an external magnetic field. When we applied a magnetic field on the same direction to the pre-magnetization direction at 225°C, one magnetic domain wall was pinned by a grain boundary and the other magnetic domain wall moved. As the results, the reverse magnetic domain shrank then annihilated. When we cut the applied magnetic field, the reverse magnetic domain generated at almost the same location. On the other hand, when we applied a magnetic field to the foils in the opposite direction, the reverse domain started to grow, i.e., magnetic domain walls started to move. The observation results of the shrink or growth of the reverse domain showed that the pinning effect of grain boundary against domain wall motion would be different depending on the applied magnetic field direction. Moreover, domain walls was observed to be pinned by grain boundaries at elevated temperature, so that the coercivity of Nd-Fe-B magnet would occur by pinning mechanism.

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