Magnetic Technique for Nondestructive Evaluation of Residual Stresses

A technique has been designed for measuring planar components of stray fields from ferromagnetic samples placed in a constant magnetizing field. The technique is based on recording the field of magnetization reversal of a thin magnetic film with the small coercive force being the sensor device of a microwave detector. The possibility of measuring the deformation inhomogeneities caused by mechanical treatment when manufacturing products from ferromagnetic materials is demonstrated. The results of the magnetic measurements agree with the data from X-ray diffraction analysis.

ドイツの医療保障の動向と介護保険

第4回　最終回　ヨーロッパ諸国の医療保障の現

Ferromagnetic resonance force spectroscopy of individual sub-micron size samples

We review how a magnetic resonance force microscope (MRFM) can be applied to perform ferromagnetic resonance (FMR) spectroscopy of \emph{individual} sub-micron size samples. We restrict our attention to a thorough study of the spin-wave eigen-modes excited in permalloy (Py) disks patterned out of the same 43.3 nm thin film. The disks have a diameter of either 1.0 or $0.5 \mu$m and are quasi-saturated by a perpendicularly applied magnetic field. It is shown that \emph{quantitative} spectroscopic information can be extracted from the MRFM measurements. In particular, the data are extensively compared with complementary approximate models of the dynamical susceptibility: i) a 2D analytical model, which assumes an homogeneous magnetization dynamics along the thickness and ii) a full 3D micromagnetic simulation, which assumes an homogeneous magnetization dynamics below a characteristic length scale $c$ and which approximates the cylindrical sample volume by a discretized representation with regular cubic mesh of lateral size $c=3.9$ nm. In our analysis, the distortions due to a breaking of the axial symmetry are taken into account, both models incorporating the possibility of a small misalignment between the applied field and the normal of the disks

Ferromagnetic resonance force spectroscopy of individual submicron-size samples

We review how a magnetic-resonance force microscope (MRFM) can be applied to perform ferromagnetic resonance spectroscopy of individual submicron-size samples. We restrict our attention to a thorough study of the spin-wave eigenmodes excited in Permalloy (Py) disks patterned out of the same 43.3-nm-thin film. The disks have a diameter of either 1.0 or 0.5 μm and are quasisaturated by a perpendicularly applied magnetic field. It is shown that quantitative spectroscopic information can be extracted from the MRFM measurements. In particular, the data are extensively compared with complementary approximate models of the dynamical susceptibility: (i) a two-dimensional analytical model, which assumes a homogeneous magnetization dynamics along the thickness, and ii) a full three-dimensional micromagnetic simulation, which assumes a homogeneous magnetization dynamics below a characteristic length scale c and approximates the cylindrical sample volume by a discretized representation with regular cubic mesh of lateral size c=3.9 nm. In our analysis, the distortions due to a breaking of the axial symmetry are taken into account; both models incorporating the possibility of a small misalignment between the applied field and the normal of the disks. © 2008 The American Physical Society

Miniaturized bandpass filter based on double spiral stripline resonators

Поступила: 01.03.2021. Принята в печать: 18.03.2021.Received: 01.03.2021. Accepted: 18.03.2021.Разработана новая миниатюрная монолитная конструкция полосно-пропускающего фильтра, которая может изготавливаться по технологии многослойных печатных плат. Каждый резонатор в фильтре образован вставленными друг в друга металлическими спиралями левой и правой закрутки, у которых одна пара смежных концов замкнута на экран, а другая – свободна. Витки из полосковых проводников в форме одинаковых прямоугольных рамок выполнены на диэлектрических пластинах и располагаются в многослойной структуре строго друг под другом с чередованием витков левой и правой спиралей. Конструкция фильтра на таких многопроводниковых двуспиральных резонаторах имеет не только малые размеры, но и обладает высокой селективностью, что доказывают измеренные характеристики фильтра четвертого порядка, резонаторы которого изготовлены на пяти диэлектрических слоях из материала RO4350BTM. Центральная частота полосы пропускания фильтра f0 = 60 МГц, ее относительная ширина Δf / f0 = 18 %, при этом размеры устройства 34 × 16.5 × 4.3 мм3 (0.007λ0 × 0.003λ0 × 0.001λ0, где λ0 – длина волны в вакууме на частоте f0). Фильтр обладает протяженной полосой заграждения, которая по уровню –38 дБ простирается до частоты 16f0.A new miniature monolithic bandpass filter, which can be manufactured using multilayer standard all-PCB technology, is presented. Each resonator in the filter is formed by metal spirals of the left and right twist inserted into each other, in which one pair of adjacent ends is grounded, and the other is free. Spiral inductors have the form of identical rectangular frames and are designed on dielectric substrates, located on a multilayer structure strictly under each other with alternating turns of the left and right spirals. The design of the filter based on such multilayer double-spiral resonators is both small in size, and highly selective, which is proved by the measured characteristics of the fourth order filter fabricated at seven dielectric layers of RO4350B material. The filter has the central frequency of the passband f0 = 60 MHz, and the fractional bandwidth Δf / f0 = 18%, while the size of the device is of the device are only 34 × 16.5 × 4.3 mm3 (0.007λ0 × 0.003λ0 × 0.001λ0, where λ0 is the wavelength at the center frequency f0). The filter has a wide stopband, which extends up to the frequency of 16f0 at a level of –38 dB.Финансирование работы: Работа выполнена при финансовой поддержке Министерства науки и высшего образования России по госзаданию № FEFE-2020-0013 «Развитие теории самоконфигурирующихся алгоритмов машинного обучения для моделирования и прогнозирования характеристик компонентов сложных систем».This study was supported by the Ministry of Science and Higher Education of the Russian Federation, state assignment no. FEFE-2020-0013 “Development of the Theory of Self-Configurable Machine-Learning Algorithms for Simulating and Predicting Characteristics of Complex Systems.

Reflective Power Limiter for X-band with HTSC switching element

his paper presents a new type of power limiter (PL), using superconducting – to – normal state phase transition in HTSC. The presented device differs from the existing ones mainly in the reflective principle of its operation. In fact the PL is a three-resonator microstrip filter, whose resonators are configured and arranged in such a manner that coupling coefficient between the outer resonators equals zero, and the inner one has a gap in the middle section shunted by a HTS film element. In small signal mode, the HTS element is in low-loss state, and the device is essentially a three-pole filter with low transmission loss. When the level of the signal exceeds the threshold, HTS element transits to the high-loss state, and Q-factor of the inner resonator falls, breaking the coupling in the structure. This leads to the corresponding increase in PL’s transmission loss due to reflection. The more the level of incoming power, the more does the Q-factor fall. The PL operating frequency is 8 GHz with 8.5% fractional bandwidth. It remains operable up to 40 W of input power, providing 38 dB limitation

Reflective Power Limiter for X-band with HTSC switching element

his paper presents a new type of power limiter (PL), using superconducting – to – normal state phase transition in HTSC. The presented device differs from the existing ones mainly in the reflective principle of its operation. In fact the PL is a three-resonator microstrip filter, whose resonators are configured and arranged in such a manner that coupling coefficient between the outer resonators equals zero, and the inner one has a gap in the middle section shunted by a HTS film element. In small signal mode, the HTS element is in low-loss state, and the device is essentially a three-pole filter with low transmission loss. When the level of the signal exceeds the threshold, HTS element transits to the high-loss state, and Q-factor of the inner resonator falls, breaking the coupling in the structure. This leads to the corresponding increase in PL’s transmission loss due to reflection. The more the level of incoming power, the more does the Q-factor fall. The PL operating frequency is 8 GHz with 8.5% fractional bandwidth. It remains operable up to 40 W of input power, providing 38 dB limitation

Study of the fields scattered by a periodic strip structure of thin magnetic films

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Components of the fields scattered by a periodic planar strip structure of thin magnetic films possessing a uniaxial magnetic anisotropy in the plane have been calculated using the phenomenological model. Regularities in the dependence of these fields on the design parameters of the structure have been studied. The results obtained agree with the numerical analysis of the micromagnetic model of this structure. It has been shown that, near the edges of strips magnetized orthogonally to the major axis, the components of the scattered field can exceed the external magnetizing field by a few orders of magnitude. This fact makes it possible to design highly efficient magnetoresistive elements on the basis of a strip structure of magnetic films and thin semiconductor films

A New Approach to Determination of Equilibrium Magnetization in Magnetic Nanostructures

Представлен новый подход к определению равновесного состояния намагниченности в дискретной модели ферромагнетика. Для решения этой проблемы мы сводим ее к системе линейных неод- нородных уравнений с множителями Лагранжа. Возможность нахождения численных решений таких систем показана применением модифицированного степенного метода. Эффективность данного подхода подтверждается примерами моделирования магнитной микроструктуры и про- цессов перемагничивания в наноструктурированной тонкой магнитной пленке.A new approach to determination of the equilibrium magnetization in discrete model of a ferromagnetic is presented. Solving this problem is reduced to a system of linear inhomogeneous equations with Lagrange multipliers. The possibility of finding the numerical solutions of such systems is shown by applying of a modified power method. The efficiency of this approach is proved by examples of modelling magnetic microstructure and magnetization reversal process in a nanostructured thin magnetic film