RF magnetron sputtered (BiDy)3(FeGa)5O12:Bi2O3 composite garnet-oxide materials possessing record magneto-optic quality in the visible spectral region

Bismuth-substituted iron garnets are considered to be the most promising magneto-optical materials because of their excellent optical transparency and very high magneto-optical figures of merit in the near-infrared spectral region. However, the practical application of garnets in the visible and short-wavelength infrared parts of spectrum is currently limited, due to their very high optical absorption (especially in sputtered films) in these spectral regions. In this paper, we identify the likely source of excess absorption observed in sputtered garnet films in comparison with epitaxial layers and demonstrate (Bi,Dy)(3)(Fe,Ga)(5)O(12): Bi(2)O(3) composites possessing record MO quality in the visible region

Magnetooptical effects in two dimensional photonic crystals

Magnetooptical properties of materials with periodically modulated dielectric constant — photonic crystals (or photonic band gap materials) have been examined with relation to their possible applications for the control of electromagnetic radiation in the integrated optics devices. For this investigation we propose the original theoretical approach based on the perturbation theory. Magnetooptical Faraday and Voigt effects have been studied near extremum points of photonic bands where their significant increase takes place. Basing on the elaborated theory, some experimental results are discussed. Experimental frequency dependence Faraday rotation angle agrees well with our theoretical predictions.Магнитооптические свойства материалов с периодически модулированной диэлектрической постоянной — фотонных кристаллов (или материалов с фотонной запрещенной зоной) исследованы с точки зрения возможности их применения для управления электромагнитным излучением в устройствах интегральной оптики. Для этого исследования предложен новый теоретический подход, основанный на теории возмущений. Исследованы магнитооптические эффекты Фарадея и Фойгта вблизи экстремальных точек фотонных зон, где имеет место их значительное усиление. На основе разработанной теории обсуждаются некоторые экспериментальные результаты. Экспериментальная частотная зависимость фарадеевского угла вращения хорошо согласуется с теоретическими предсказаниями.Магнітооптичні властивості матеріалів з періодично модульованою дієлєктричною константою — фотонних кристалів (або матеріалів з фотонною забороненою зоною) досліджено з точки зору можливості їх застосування для управління електромагнітним випромінюванням у пристроях інтегральної оптики. Для цього дослідження запропоновано новий теоретичний підхід, оснований на теорії збурень. Досліджено магнитооп-тичні ефекти Фарадея та Фойгта поблизу екстремальних точок фотонних зон, де має місце їх значне посилення. На основі розробленої теории обговорюються деякі експериментальні результати. Експериментальна частотна залежність фарадеївського кута обертання добре узгоджується з теоретичними передбаченнями

Scanning near-field optical microscopy of magnetic structures in magnetic films

Magnetooptical observation of magnetic domain walls in iron-garnet films by scanning near field optical microscopy has been studied to reveal the advantages of the near-field imaging in terms of spatial resolution. Recent experiments have shown that in case of 5 to 10 μm thick magnetic films, near field observation of domain structures does not provide obvious spatial resolution increase as compared to the conventional optical microscopy. Theoretical analysis based on the Green functions method revealed that the film thickness plays a crucial role in this effect. Qualitative explanation of the resolution deterioration with the increasing film thickness is also given.Магнитооптическое наблюдение границ магнитных доменов в пленках железных гранатов способом ближне-полевой сканирующей оптической микроскопии исследовано с точки зрения обнаружения преимуществ ближне-полевого изображения в отношении пространственного разрешения. Последние эксперименты показали, что ближнеполевое исследование доменной структуры магнитных пленок толщиной 5-10 мкм не обеспечивает существенного повышения пространственного разрешения по сравнению с обычной оптической микроскопией. Теоретический анализ на основе функций Грина показывает, что решающую роль в этом эффекте играет толщина пленки. Представлено также качественное объяснение ухудшения разрешения с увеличением толщины пленки.Магнітооптичне спостереження меж магнітних домєнів у плівках залізних гранатів способом ближньо-польової сканувальної оптичної мікроскопії досліджено з точки зору виявлення переваг ближньо-польового зображення стосовно до просторового розрішен-ня. Недавні експерименти показали, що ближньо-польове дослідження доменної структури магнітних плівок товщиною 5-10 мкм не забезпечує істотного підвищення просторового розрішення у порівнянні зі звичайною оптичною мікроскопією. Теоретичний аналіз на основі функцій Гріна показує, що вирішальну роль у цьому ефекті відіграє товщина плівки. Представлено також якісне пояснення погіршення розрішення зі збільшенням товщини плівки

Superconducting Spin Valves Based on a Single Spiral Magnetic Layer

International audienceA detailed investigation of a superconducting spin-triplet valve is presented. This spin valve consists of a superconducting film covering a metal with an intrinsic spiral magnetic order, which could result from competing isotropic exchanges or, if the crystal lattice breaks central symmetry, from asymmetric Dzyaloshinskii-Moriya exchange. Depending on the anisotropy, such a metal may change its magnetization either from a spiral to uniform order, as seen in Ho and Er, or in the direction of the spiral itself, as in crystals of the B20-type structure [such as MnSi, (Fe,Co)Si, FeGe, etc.]. The nonuniform magnetic order controls the appearance of long-range triplet superconducting correlations at strong exchange fields, affecting the detailed character of the proximity effect. We show that the magnetic control of the spin-valve behavior can also be obtained from moderately low exchange fields (typically associated to negligible long-range triplet correlations), thanks to an orientation-dependent averaging mechanism of the magnetic inhomogeneity on the scale of the Cooper pairs. Our numerical calculations reveal that the spin-valve effect is in fact magnified at moderately low exchange fields, when the exchange splitting in the spiral magnet is comparable to the superconducting gap, and the spiral period is less than or equal to the superconducting coherence length in the magnet multiplied by 2π

Quantum paradigm of the foldover magnetic resonance

The explosive development of quantum magnonics requires the consideration of several previously known effects from a new angle. In particular, taking into account the quantum behavior of magnons is essential at high excitations of the magnetic system, under the conditions of the so-called phenomenon of “foldover” (bi-stable) magnetic resonance. Previously, this effect was considered in the quasi-classical macrospin approximation. However, at large angles of magnetization precession, the magnon density exceeds the critical value for the formation of a magnon Bose condensate (mBEC). Naturally, this purely quantum phenomenon does not exist in the classical approximation. In addition, mBEC leads to superfluid transfer of magnetization, which suppresses the macroinhomogeneity of the samples. The experiments presented in the article show that quantum phenomena well describes the experimental results of nonlinear magnetic resonance in yttrium iron garnet. Thus, we remove the questions that arose earlier when considering this effect without taking into account quantum phenomena. This discovery paves the way for many quantum applications of supermagnonics, such as the magnetic Josephson effect, long-range spin transport, Q-bits, quantum logic, magnetic sensors, and others

Long-Lived Induction Signal in Yttrium Iron Garnet

© 2020, Pleiades Publishing, Inc. The results of the experiments on an yttrium iron garnet film have been reported, demonstrating two types of long-lived free induction signals. The first type corresponds well to signals appearing because of the superfluid transfer of magnons, which was previously detected in antiferromagnetic superfluid 3He-B. The second, ultra-long-lived, signal also has a number of properties of coherent precession. However, it is fundamentally different from the ultra-long-lived signal in 3He-B. The mechanism of formation of the ultra-long-lived signal in yttrium iron garnet has not yet been theoretically explained

Plasmonic layer-selective all-optical switching of magnetization with nanometer resolution

Contains fulltext : 209229.pdf (publisher's version ) (Open Access

Valley polarization of trions in monolayer MoSe2 interfaced with bismuth iron garnet

Interfacing atomically thin van der Waals semiconductors with magnetic substrates enables additional control on their intrinsic valley degree of freedom and provides a promising platform for the development of novel valleytronic devices for information processing and storage. Here we study circularly polarized photoluminescence in heterostructures of monolayer MoSe2 and thin films of ferrimagnetic bismuth iron garnet (BIG). We observe strong emission from charged excitons with circular polarization opposite to that of the pump and demonstrate contrasting response to left and right circularly polarized excitation, associated with finite out-of-plane magnetization in the substrate. We propose a theoretical model accounting for magnetization-induced imbalance of charge carriers in the two valleys of MoSe2, as well as for valley-switching scattering from B to A excitons and fast formation of trions with extended valley relaxation times, which shows excellent agreement with the experimental data. Our results establish monolayer MoSe2 interfaced with BIG as a promising system for valley control of charged excitons