scholarly journals The Magnetization Reversal Processes Of Bulk (Nd, Y)-(Fe, Co)-B Alloy In The As-Quenched State

2015 ◽  
Vol 60 (3) ◽  
pp. 1587-1590
Author(s):  
M. Dośpiał ◽  
M. Nabiałek ◽  
M. Szota ◽  
J. Gondro
Keyword(s):  
Magnetic Field ◽  
Magnetization Reversal ◽  
Domain Walls ◽  
Differential Susceptibility ◽  
Exchange Interactions ◽  
Magnetization Component ◽  
Moment Vector ◽  
Magnetic Moment Vector ◽  
Irreversible Magnetization ◽  
Reversible Rotation

Abstract The magnetization reversal processes of bulk Fe64Co5Nd6Y6B19 alloy in the as-quenched state have been investigated. From the analysis of the initial magnetization curve and differential susceptibility versus an internal magnetic field it was deduced, that the main mechanism of magnetization reversal process is the pinning of domain walls at the grain’s boundaries of the Nd2Fe14B phase. Basing on the dependence of the reversible magnetization component as a function of magnetic field it was found that reversible rotation of a magnetic moment vector and motion of domain walls in multi-domain grains result in high initial values of the reversible component. The presence of at least two maxima on differential susceptibility of irreversible magnetization component in function of magnetic field imply existence of few pinning sites of domain walls in Fe64Co5Nd6Y6B19 alloy. The dominant interactions between particles have been determined on the basis of the Wohlfarth dependence. Such a behavior of Wohlfarth’s plot implies that the dominant interaction between grains becomes short range exchange interactions.

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.

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.

Imaging of ferroelectric domain walls by electron holography

1992 ◽  
Vol 50 (1) ◽  
pp. 246-247
Author(s):  
Xiao Zhang
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Domain Walls ◽  
Ferroelectric Domain ◽  
Object Wave ◽  
Electron Holography ◽  
High Resolution Imaging ◽  
Quantitative Measurements ◽  
Resolution Imaging ◽  
Electron Microscopes

Electron holography has recently been available to modern electron microscopy labs with the development of field emission electron microscopes. The unique advantage of recording both amplitude and phase of the object wave makes electron holography a effective tool to study electron optical phase objects. The visibility of the phase shifts of the object wave makes it possible to directly image the distributions of an electric or a magnetic field at high resolution. This work presents preliminary results of first high resolution imaging of ferroelectric domain walls by electron holography in BaTiO3 and quantitative measurements of electrostatic field distribution across domain walls.

scholarly journals Subsystem domination influence on magnetization reversal in designed magnetic patterns in ferrimagnetic Tb/Co multilayers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Łukasz Frąckowiak ◽  
Feliks Stobiecki ◽  
Gabriel David Chaves-O’Flynn ◽  
Maciej Urbaniak ◽  
Marek Schmidt ◽  
...  
Keyword(s):  
Domain Wall ◽  
Magnetization Reversal ◽  
Domain Walls ◽  
Compensation Point ◽  
Relative Sign ◽  
Reversal Process ◽  
Effective Magnetization ◽  
Domain Wall Propagation ◽  
Characteristic Features ◽  
Magnetization Reversal Process

AbstractRecent results showed that the ferrimagnetic compensation point and other characteristic features of Tb/Co ferrimagnetic multilayers can be tailored by He+ ion bombardment. With appropriate choices of the He+ ion dose, we prepared two types of lattices composed of squares with either Tb or Co domination. The magnetization reversal of the first lattice is similar to that seen in ferromagnetic heterostructures consisting of areas with different switching fields. However, in the second lattice, the creation of domains without accompanying domain walls is possible. These domain patterns are particularly stable because they simultaneously lower the demagnetizing energy and the energy associated with the presence of domain walls (exchange and anisotropy). For both lattices, studies of magnetization reversal show that this process takes place by the propagation of the domain walls. If they are not present at the onset, the reversal starts from the nucleation of reversed domains and it is followed by domain wall propagation. The magnetization reversal process does not depend significantly on the relative sign of the effective magnetization in areas separated by domain walls.

scholarly journals Controllable field-free switching of perpendicular magnetization through bulk spin-orbit torque in symmetry-broken ferromagnetic films

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xuejie Xie ◽  
Xiaonan Zhao ◽  
Yanan Dong ◽  
Xianlin Qu ◽  
Kun Zheng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Domain Walls ◽  
Single Layer ◽  
Ferromagnetic Film ◽  
Effective Field ◽  
Composition Gradient ◽  
Spin Orbit ◽  
Interlayer Exchange Coupling ◽  
Magnetization Switching ◽  
Perpendicular Magnetization

AbstractProgrammable magnetic field-free manipulation of perpendicular magnetization switching is essential for the development of ultralow-power spintronic devices. However, the magnetization in a centrosymmetric single-layer ferromagnetic film cannot be switched directly by passing an electrical current in itself. Here, we demonstrate a repeatable bulk spin-orbit torque (SOT) switching of the perpendicularly magnetized CoPt alloy single-layer films by introducing a composition gradient in the thickness direction to break the inversion symmetry. Experimental results reveal that the bulk SOT-induced effective field on the domain walls leads to the domain walls motion and magnetization switching. Moreover, magnetic field-free perpendicular magnetization switching caused by SOT and its switching polarity (clockwise or counterclockwise) can be reversibly controlled in the IrMn/Co/Ru/CoPt heterojunctions based on the exchange bias and interlayer exchange coupling. This unique composition gradient approach accompanied with electrically controllable SOT magnetization switching provides a promising strategy to access energy-efficient control of memory and logic devices.

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