FORC-Diagram Analysis for a Step-like Magnetization Reversal in Nanopatterned Stripe Array

The fabrication approach of a magnonic crystal with a step-like hysteresis behavior based on a uniform non-monotonous iron layer made by shadow deposition on a preconfigured substrate is reported. The origin of the step-like hysteresis loop behavior is studied with local and integral magnetometry methods, including First-Order Reversal Curves (FORC) diagram analysis, accompanied with magnetic microstructure dynamics measurements. The results are validated with macroscopic magnetic properties and micromagnetic simulations using the intrinsic switching field distribution model. The proposed fabrication method can be used to produce magnonic structures with the controllable hysteresis plateau region’s field position and width that can be used to control the magnonic crystal’s band structure by changing of an external magnetic field.

Anti-function solution of uniaxial anisotropic Stoner-Wohlfarth model

The anti-trigonometric function is used to strictly solve the uniaxial anisotropic Stoner-Wohlfarth (SW) model, which can obtain the relation of the angle α (θ) between the magnetization (the anisotropy field) and the applied magnetic field. Using this analytic solution, the hysteresis loops of uniaxial anisotropic SW particles magnetized in typical directions could be numerically calculated. Then, the hysteresis loops are obtained in randomly distributed SW particle ensembles while ignoring the dipole interaction among them with the analytic solution. Finally, the correctness of the analytic solution is verified by the exact solutions of remanence, switching field, and coercivity from SW model. The analytic solution provides an important reference for understanding the magnetizing and magnetization reversal processes of magnetic materials.

Electric-field-tunable linear unipolar magnetic switch based on a spin-valve multiferroic heterostructure

This work reports an energy-efficient strategy for realizing linear unipolar giant magnetoresistance (GMR) switch by using electric fields (E-fields). Herein, a modified spin-valve (SV) structure of double antiferromagnetic (AFM) pinning layers was adopted. Since the magnetization direction of ferromagnetic (FM) layer can be controlled via the strain-mediated magnetoelectric (ME) effect, a multiferroic heterostructure of SV/PMN-PT was fabricated. By applying an E-field on the PMN-PT substrate, an effective magnetic field Heff was produced along the [1-10] direction of PMN-PT. It can turn the magnetic moments of FM layer toward [1-10] direction. Accordingly, a linear GMR curve with a wide sensing field range was achieved. This E-field-induced linear magnetic switch can satisfy the demand for different switching field ranges in the same application system.

Surface Magnetization Reversal of Wiegand Wire Measured by the Magneto-Optical Kerr Effect

The Wiegand wire is known to exhibit a unique feature of fast magnetization reversal in the magnetically soft region accompanied by a large Barkhausen jump. We clarified a significant difference between the magnetization reversals at the surface and at the entire cross section of a Wiegand wire. We conducted magnetization measurements based on the magneto-optical Kerr effect and applied conventional methods to determine the magnetization curves. The switching field of the magnetization reversal at the surface was greater than that at the initiation of a large Barkhausen jump. Our analysis suggests that the outer surface layer exhibits low coercivity.

System analysis of the echelon scheme for the formation of the switching field of the centralized video surveillance node of office infocommunication systems

Введено понятие эшелонной схемы построения коммутационного поля центрального узла систем IP-видеонаблюдения и выполнена соответствующая ей модернизация типовых принципов расположение образующего его оборудования. Обоснована возможность размещения оборудования центрального узла в 19-дюймовом шкафу шириной 600 мм при количестве телекамер вплоть до 480. Проведена оценка средней длины коммутационных шнуров и показано, что обращение к эшелонной схеме дает практически двукратное сокращение этого параметра, что улучшает условия администрирование системы. The concept of an echelon scheme for constructing the switching field of the central node of IP-video surveillance systems was introduced and the corresponding modernization of the standard principles of the arrangement of the equipment forming it was performed. The possibility of placing the equipment of the central unit in a 19-inch cabinet 600 mm wide with the number of cameras up to 480 was substantiated. The estimation of the average length of the patch cords was carried out and was shown that the use of the echelon scheme gave an almost double reduction of this parameter that improved the conditions for system administration.

Actuating a Magnetic Shape Memory Element Locally with a Set of Coils

The local actuation of a magnetic shape memory (MSM) element as used in an MSM micropump is considered. This paper presents the difference between an electromagnetic driver and a driver that uses a rotating permanent magnet. For the magnetic field energy of the permanent magnetic drive, the element takes in a significant stray field. In a particular case, energy reduction was 12.7 mJ. For an electromagnetic drive with an identical size of the MSM element, the total magnetic field energy created by the system was 2.28 mJ. Attempts to experimentally nucleate twins in an MSM element by energizing an electromagnetic drive failed even though the local magnetic field exceeded the magnetic switching field. The energy variation is an order of magnitude smaller for the electromagnetic drive, and it does not generate the necessary driving force. It was assumed in previous work that the so-called magnetic switching field presents a sufficient requirement to nucleate a twin and, thus, to locally actuate an MSM element. Here, we show that the total magnetic field energy available to the MSM element presents another requirement.