Resonant phonon-magnon interactions in free-standing metal-ferromagnet multilayer structures

We analyze resonant magneto-elastic interactions between standing perpendicular spin wave modes (exchange magnons) and longitudinal acoustic phonon modes in free-standing hybrid metal-ferromagnet bilayer and trilayer structures. Whereas the ferromagnetic layer acts as a magnetic cavity, all metal layers control the frequencies and eigenmodes of acoustic vibrations. The here proposed design allows for achieving and tuning the spectral and spatial modes overlap between phonons and magnons that results in their strong resonant interaction. Realistic simulations for gold-nickel multilayers show that sweeping the external magnetic field should allow for observing resonantly enhanced interactions between individual magnon and phonon modes in a broad range of frequencies spanning from tens of GHz up to several hundreds of GHz, which can be finely tuned through the multilayer design. Our results would enable the systematic study and the deep understanding of resonantly enhanced magneto-elastic coupling between individual phonon and magnon modes up to frequencies of great contemporary fundamental and applied interest.Comment: 9 pages, 6 figure

The 2022 magneto-optics roadmap

Magneto-optical (MO) effects, viz. magnetically induced changes in light intensity or polarization upon reflection from or transmission through a magnetic sample, were discovered over a century and a half ago. Initially they played a crucially relevant role in unveiling the fundamentals of electromagnetism and quantum mechanics. A more broad-based relevance and wide-spread use of MO methods, however, remained quite limited until the 1960s due to a lack of suitable, reliable and easy-to-operate light sources. The advent of Laser technology and the availability of other novel light sources led to an enormous expansion of MO measurement techniques and applications that continues to this day (see section 1). The here-assembled roadmap article is intended to provide a meaningful survey over many of the most relevant recent developments, advances, and emerging research directions in a rather condensed form, so that readers can easily access a significant overview about this very dynamic research field. While light source technology and other experimental developments were crucial in the establishment of today's magneto-optics, progress also relies on an ever-increasing theoretical understanding of MO effects from a quantum mechanical perspective (see section 2), as well as using electromagnetic theory and modelling approaches (see section 3) to enable quantitatively reliable predictions for ever more complex materials, metamaterials, and device geometries. The latest advances in established MO methodologies and especially the utilization of the MO Kerr effect (MOKE) are presented in sections 4 (MOKE spectroscopy), 5 (higher order MOKE effects), 6 (MOKE microscopy), 8 (high sensitivity MOKE), 9 (generalized MO ellipsometry), and 20 (Cotton–Mouton effect in two-dimensional materials). In addition, MO effects are now being investigated and utilized in spectral ranges, to which they originally seemed completely foreign, as those of synchrotron radiation x-rays (see section 14 on three-dimensional magnetic characterization and section 16 on light beams carrying orbital angular momentum) and, very recently, the terahertz (THz) regime (see section 18 on THz MOKE and section 19 on THz ellipsometry for electron paramagnetic resonance detection). Magneto-optics also demonstrates its strength in a unique way when combined with femtosecond laser pulses (see section 10 on ultrafast MOKE and section 15 on magneto-optics using x-ray free electron lasers), facilitating the very active field of time-resolved MO spectroscopy that enables investigations of phenomena like spin relaxation of non-equilibrium photoexcited carriers, transient modifications of ferromagnetic order, and photo-induced dynamic phase transitions, to name a few. Recent progress in nanoscience and nanotechnology, which is intimately linked to the achieved impressive ability to reliably fabricate materials and functional structures at the nanoscale, now enables the exploitation of strongly enhanced MO effects induced by light–matter interaction at the nanoscale (see section 12 on magnetoplasmonics and section 13 on MO metasurfaces). MO effects are also at the very heart of powerful magnetic characterization techniques like Brillouin light scattering and time-resolved pump-probe measurements for the study of spin waves (see section 7), their interactions with acoustic waves (see section 11), and ultra-sensitive magnetic field sensing applications based on nitrogen-vacancy centres in diamond (see section 17). Despite our best attempt to represent the field of magneto-optics accurately and do justice to all its novel developments and its diversity, the research area is so extensive and active that there remains great latitude in deciding what to include in an article of this sort, which in turn means that some areas might not be adequately represented here. However, we feel that the 20 sections that form this 2022 magneto-optics roadmap article, each written by experts in the field and addressing a specific subject on only two pages, provide an accurate snapshot of where this research field stands today. Correspondingly, it should act as a valuable reference point and guideline for emerging research directions in modern magneto-optics, as well as illustrate the directions this research field might take in the foreseeable future

Millijoule pulse energy 100-nanosecond Er-doped fiber laser

International audienceWe report, for the first time to our knowledge, on a single-mode millijoule-level 100-nanosecond Er-doped fiber laser operating near 1550 nm. The system features a newly developed 35-μm-core Yb-free double-clad Er-doped fiber based on P2O5-Al2O3-SiO2 glass matrix and produces pulses with energy as high as 1 mJ at repetition rates of 1–10 kHz

Yb^3+-doped double-clad phosphate fiber for 976 nm single-frequency laser amplifiers

Highly ytterbium (Yb3+)-doped double-clad phosphate fiber was fabricated for the investigation of power scaling of a 976 nm single-frequency laser. Over 3 W single-frequency laser output power was obtained with gain fibers shorter than 10 cm. Our experimental results show that Yb3+-doped phosphate fiber is a promising gain medium for 976 nm laser amplifiers. (C) 2017 Optical Society of AmericaNational Aeronautics and Space Administration (NASA) Small Business Technology Transfer (STTR) Phase II [NNX15CP19C]; National Science Foundation Engineering Research Center for Integrated Access Networks [EEC-0812072]; Technology Research Initiative Fund (TRIF) Photonics Initiative of the University of ArizonaOpen access journal.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Оптимизация амплитуды магнитоупругих колебаний в ферритовой пластине

The maximum amplitudes of elastic vibrations, depending on the material parameters and parameters of external fields in a normally magnetized anisotropic magnetic plate at its excitation by radio frequency magnetic field were obtained. For this purpose we used the method "simulated annealing". The three- dimensional graphics of resonant surfaces of elastic oscillations on the thickness of the plate, on the elastic constants, magnetic damping constant and the magnetoelastic constant in the area of maximum amplitudes found by the simulated annealing algorithm were constructed and explainedНайдены максимумы амплитуд упругих колебаний в зависимости от материальных констант и параметров постоянного и переменного магнитных полей в нормально намагниченной анизотроп- ной ферритовой пластине при ее возбуждении радиочастотным магнитным полем. Для решения этой задачи использован алгоритм "имитация отжига". Построены и объяснены трехмерные графики резонансных поверхностей упругих колебаний в зависимости от толщины пластины, упругих констант, параметра магнитной диссипации и значений констант магнитоупругости в области максимальных амплитуд колебани

Спектры эффективной проницаемости и потерь в магнитных композитных пленках

The research was devoted to a studying of the spectra effective permeability and losses in the magnetic composite films at different ratios of concentrations of metal and dielectric. The effective permeability was determined from the ratio of capacitance of the capacitor with a film (magnetic metal-dielectric) and without film. The results the permeability spectra for films for different composition and concentration of metals and dielectrics showed that they had similar trend of behavior in generalИсследование посвящено изучению спектров эффективной проницаемости и потерь в магнитных композитных пленках при различных соотношениях концентраций металлической и диэлектри- ческой фаз. Эффективная проницаемость определяется из соотношения емкости конденсатора с пленкой (магнитный металл-диэлектрик) и без пленки. В результате спектры проницаемости для пленок различного состава и концентраций металлов и диэлектриков показали, что они в целом имеют подобные тенденции в поведени

Оптимизация амплитуды магнитоупругих колебаний в ферритовой пластине

The maximum amplitudes of elastic vibrations, depending on the material parameters and parameters of external fields in a normally magnetized anisotropic magnetic plate at its excitation by radio frequency magnetic field were obtained. For this purpose we used the method "simulated annealing". The three- dimensional graphics of resonant surfaces of elastic oscillations on the thickness of the plate, on the elastic constants, magnetic damping constant and the magnetoelastic constant in the area of maximum amplitudes found by the simulated annealing algorithm were constructed and explainedНайдены максимумы амплитуд упругих колебаний в зависимости от материальных констант и параметров постоянного и переменного магнитных полей в нормально намагниченной анизотроп- ной ферритовой пластине при ее возбуждении радиочастотным магнитным полем. Для решения этой задачи использован алгоритм "имитация отжига". Построены и объяснены трехмерные графики резонансных поверхностей упругих колебаний в зависимости от толщины пластины, упругих констант, параметра магнитной диссипации и значений констант магнитоупругости в области максимальных амплитуд колебани

Спектры эффективной проницаемости и потерь в магнитных композитных пленках

The research was devoted to a studying of the spectra effective permeability and losses in the magnetic composite films at different ratios of concentrations of metal and dielectric. The effective permeability was determined from the ratio of capacitance of the capacitor with a film (magnetic metal-dielectric) and without film. The results the permeability spectra for films for different composition and concentration of metals and dielectrics showed that they had similar trend of behavior in generalИсследование посвящено изучению спектров эффективной проницаемости и потерь в магнитных композитных пленках при различных соотношениях концентраций металлической и диэлектри- ческой фаз. Эффективная проницаемость определяется из соотношения емкости конденсатора с пленкой (магнитный металл-диэлектрик) и без пленки. В результате спектры проницаемости для пленок различного состава и концентраций металлов и диэлектриков показали, что они в целом имеют подобные тенденции в поведени

All-fiber mode-locked laser at 0.98 µm

We developed a highly efficient double-clad Yb-doped polarization-maintaining fiber to be implemented for small-signal amplification near 0.976 mu m. The fiber was designed to have a relatively small mode field diameter compatible with standard step-index single-mode optical fibers. Another feature of the fiber was a small threshold for 0.976 mu m signal amplification, which was achieved by a creation of a thin inner cladding (80 mu m diameter). The unique design of the fiber allowed us to construct successfully an all-fiber picoseconds mode-locked laser at 0.98 mu m for the first time to the best of our knowledge.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Er-Doped Tapered Fiber Amplifier for High Peak Power Sub-ns Pulse Amplification

A tapered Er-doped fiber amplifier for high peak power pulses amplification has been developed and tested. The core diameter changed from 15.8 µm (mode field diameter (MFD) 14.5 µm) to 93 µm (MFD 40 µm) along 3.7 m maintaining single-mode performance at 1555 nm (according to the S2-method, the part of the power of high-order modes does not exceed 1.5%). The amplification of 0.9 ns pulses with spectral width below 0.04 nm up to a peak power above 200 kW (limited by self-phase modulation) with a slope pump-to-signal conversion efficiency of 15.6% was demonstrated