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Metasurfaces are established tools for manipulating light and enhancing light-matter interactions. However, the loss of conventional meta-atoms usually limits the performance potential of metasurfaces. In this study, we propose a class of metasurfaces based on discretized meta-atoms able to mitigate the radiative and intrinsic losses. By discretizing meta-atoms, we reduce the loss of metal metasurfaces to levels comparable to dielectric metasurfaces in the short-wavelength infrared region at the surface lattice resonance mode. Furthermore, we propose a coupling model to explain the observed reduction in loss in full agreement with the results obtained from finite-element method. We also reproduce this phenomenon using dielectric metasurface at electric and magnetic resonances in the visible region. Our finding offers valuable insights for the design and application of metasurfaces, while also providing theoretical implications for other resonance fields beyond metasurfaces. Metasurfaces are established tools for manipulating light and enhancing light-matter interactions, but the loss of conventional meta-atoms usually limits the performance potential of metasurfaces. Here, the authors propose a class of metasurfaces based on discretized meta-atoms able to mitigate the radiative and intrinsic losses, as interpreted by their built coupling model. [ABSTRACT FROM AUTHOR]

Echocardiography is recommended as a first-line diagnostic tool in patients with premature ventricular contractions (PVCs). However, standard echocardiography is not always able to identify early signs of myocardial dysfunction and cardiac magnetic resonance (CMR) may offer additional information. Since CMR has lower accessibility and higher cost compared to echocardiography, we wanted to evaluate how additional echocardiographic parameters, not included in routine examinations, perform compared to CMR in detecting signs of cardiomyopathy in PVC patients with normal findings at a standard echocardiogram. We compared CMR findings and results from an extended echocardiographic examination in thirty-nine patients who had a high PVC burden. The additional echocardiographic parameters were global longitudinal strain, mechanical dispersion, ventricular–arterial coupling, integrated backscatter and left atrial activation time. Eleven patients had pathological findings at CMR. The additional echocardiographic parameters did not significantly differ between patients with or without CMR findings. However, several patients with normal CMR findings showed signs of ventricular dysfunction when evaluated with the additional echocardiographic parameters, which suggests that these could possibly offer supplementary information in the assessment of PVC patients. [ABSTRACT FROM AUTHOR]

Lattice resonances are collective modes supported by periodic arrays of nanostructures. They originate from the coherent interaction between the localized modes of the individual constituents of the array, which, for systems made of metallic nanostructures, usually correspond to the electric dipole plasmon. Unfortunately, fundamental symmetry reasons preclude a two‐dimensional (2D) arrangement of electric dipoles from absorbing more than half the incident power, thus imposing a strong limitation on the performance of conventional lattice resonances. This work introduces an innovative solution to overcome this constraint, which is based on using an array made of a unit cell containing one metallic and one dielectric nanostructure. Using a rigorous coupled dipole model, it is shown that this system can support two independent lattice resonances associated, respectively, with the electric and magnetic dipole modes of the nanostructures. By adjusting the geometrical characteristics of the array, these two lattice resonances can be meticulously aligned in the spectral domain, leading to the total absorption of the incident power. The results of this work provide clear, yet general, guidelines for the rational design of arrays sustaining lattice resonances capable of producing perfect absorption, thus leveraging the potential of these modes for applications requiring an efficient absorption of light. [ABSTRACT FROM AUTHOR]

High-index dielectric structures support electric and magnetic Mie resonance. Through careful manipulation of geometric parameters, destructive interference can be induced between electric multipole moments and toroidal multipole moments. This leads to the formation of anapoles, which are characterized by quenched scattering in the far field and giant enhancement in the near field. Here, we revisit the formation mechanism of anapole states in a single dielectric structure with a high refractive index from an eigenmode perspective. We find that scattering efficiency is mainly determined by the intrinsic phase governed by the leaky mode of the structure and the extrinsic phase induced by the frequency deviation from resonance. It is also demonstrated that the anapole modes in a two-dimensional cylinder and a three-dimensional sphere can only occur in the following two situations: (1) when only one mode is involved, the combined phase of intrinsic and extrinsic phase should be equal to 2 π at a certain frequency (anapole frequency), which is very close to the resonance frequency. Generally, these types of anapoles are low-order anapoles since low-order resonant modes (i.e., magnetic (electric) dipole and quadrupole) are well separated. (2) If two or more leaky modes are involved, the combined phase for each mode must be 2 π at the same frequency located between the two resonances. This corresponds to the high-order anapoles. It is also found that more anapole states will emerge with increasing refractive index. Our results may provide new perspectives for designing high-order anapoles with more freedom. [ABSTRACT FROM AUTHOR]

Magnetic resonance wireless power transmission consists of a source coil and relay coil (transmission coil (Tx-coil), receiving coil (Rx-coil)). The relay coil is designed with windings and a series capacitor, which are resonant with the input voltage frequency. Magnetic resonant wireless power transmission by a relay coil enables the transmission of power from a few centimeters to several meters. Recently, research has been conducted on the shape and material of each coil to increase the transmission distance. However, limitations remain with respect to increasing the transmission distance. Specifically, the optimization of the electrical characteristics of the relay coil is necessary to increase the transmission distance and improve efficiency. In this study, we configured the inductance of the relay coil to be approximately 95 μH, 270 μH, and 630 μH. Accordingly, we designed the series capacitors to have the same resonant frequency and analyzed the transmission characteristics of each relay coil. We confirmed that as the inductance increased, the transmission efficiency increased by up to 10%. The relay coil was designed to have an inductance of approximately three to six times that of the source coil (load coil). Thus, the optimal design of the relay coil is believed to be the most efficient and economical coil design. [ABSTRACT FROM AUTHOR]

Background: Brain tumor segmentation is highly contributive in diagnosing and treatment planning. Manual brain tumor delineation is a time-consuming and tedious task and varies depending on the radiologist's skill. Automated brain tumor segmentation is of high importance and does not depend on either inter- or intra-observation. The objective of this study is to automate the delineation of brain tumors from the Fluid-attenuated inversion recovery (FLAIR), T1-weighted (T1W), T2-weighted (T2W), and T1W contrast-enhanced (T1ce) magnetic resonance (MR) sequences through a deep learning approach, with a focus on determining which MR sequence alone or which combination thereof would lead to the highest accuracy therein. Methods: The BraTS-2020 challenge dataset, containing 370 subjects with four MR sequences and manually delineated tumor masks, is applied to train a residual neural network. This network is trained and assessed separately for each one of the MR sequences (single-channel input) and any combination thereof (dual- or multi-channel input). Results: The quantitative assessment of the single-channel models reveals that the FLAIR sequence would yield higher segmentation accuracy compared to its counterparts with a 0.77 ± 0.10 Dice index. As to considering the dual-channel models, the model with FLAIR and T2W inputs yields a 0.80 ± 0.10 Dice index, exhibiting higher performance. The joint tumor segmentation on the entire four MR sequences yields the highest overall segmentation accuracy with a 0.82 ± 0.09 Dice index. Conclusion: The FLAIR MR sequence is considered the best choice for tumor segmentation on a single MR sequence, while the joint segmentation on the entire four MR sequences would yield higher tumor delineation accuracy. [ABSTRACT FROM AUTHOR]

We demonstrate experimentally that a one-dimensional array of silicon nanowires periodically placed on a nickel substrate enhances the transverse magneto-optical Kerr effect (TMOKE) compared to a nickel film. The enhancement mechanism is associated with the excitation of two types of resonances: multipole Mie resonances in each nanowire and surface lattice resonances (SLRs) emerging from the periodic arrangement of the nanowires. The maximal TMOKE values reached up to 1.9 and 2.6% due to the excitation of SLR and a magnetic dipole resonance, respectively. When the SLR is excited, the spectral width of the TMOKE enhancement is narrower compared to the case of the magnetic dipole resonance. [ABSTRACT FROM AUTHOR]

The high‐frequency optical mode of α‐Fe2O3 is examined, and it is reported that Dzyaloshinskii−Moriya (DM) interaction generates a new type of torque on the magnetic resonance. Using a continuous‐wave terahertz interferometer, the optical mode spectra is measured, where the asymmetric absorption with a large amplitude and broad linewidth is observed near the magnetic transition point, Morin temperature (TM ≈ 254.3 K). Based on the spin wave model, the spectral anomaly is attributed to the DM interaction‐induced torque, enabling to extract the strength of DM interaction field of 4 T. This work opens a new avenue to characterize the spin resonance behaviors at an antiferromagnetic singular point for next‐generation and high‐frequency spin‐based information technologies. [ABSTRACT FROM AUTHOR]

The high‐frequency optical mode of α‐Fe2O3 is examined, and it is reported that Dzyaloshinskii−Moriya (DM) interaction generates a new type of torque on the magnetic resonance. Using a continuous‐wave terahertz interferometer, the optical mode spectra is measured, where the asymmetric absorption with a large amplitude and broad linewidth is observed near the magnetic transition point, Morin temperature (TM ≈ 254.3 K). Based on the spin wave model, the spectral anomaly is attributed to the DM interaction‐induced torque, enabling to extract the strength of DM interaction field of 4 T. This work opens a new avenue to characterize the spin resonance behaviors at an antiferromagnetic singular point for next‐generation and high‐frequency spin‐based information technologies. [ABSTRACT FROM AUTHOR]

Resonant excitation and manipulation of complex interactions among two or more resonances in high-index dielectric nanostructures provide great opportunities for engineering novel optical phenomena and applications. However, difficulties often arise when interpreting the observed spectra because of the overlap of the broad resonances contributed by many factors such as particle size, shape, and background index. Therefore, selective excitation of resonances that spectrally overlap with each other provides a gateway towards an improved understanding of the complex interactions. Here, we demonstrate selective excitation and enhancement of multipolar resonances of silicon nanospheres using cylindrical vector beams (CVBs) with different diameters of nanospheres and numerical apertures (NAs) of the excitations. By combining single particle spectroscopy and electrodynamic simulations, we show that the radially polarized beam can selectively excite the electric multipoles, whereas the azimuthally polarized beam can selectively excite the magnetic multipoles even though multipolar resonances are convoluted together due to their spectral overlap. Moreover, focusing the CVBs with high NA can lead to a dominant longitudinal polarization of the electric or magnetic field. We show that the enhanced longitudinal polarization with increasing NA of the radially and azimuthally polarized beams can selectively enhance the electric and magnetic multipolar resonances, respectively. Our approach can be used as a spectroscopy tool to enhance and identify multipolar resonances leading to a better understanding of light-matter interactions in other dielectric nanostructures as well as serve as a first step toward excitation of dark mode and Fano resonances in dielectric oligomers by breaking the symmetry of the nanostructures. [ABSTRACT FROM AUTHOR]

For miniaturized active metasurfaces, resonance tuning of nanoantennas is a key ingredient. Phase‐change materials (PCMs) have been established as prime candidates for non‐volatile resonance tuning enabled by a change in the refractive index around nanoantennas. Conventionally, this tuning is induced by annealing the entire sample equally and does not allow changes on a meta‐atom level. Recently, it is demonstrated that individual rodantenna resonances can be adjusted by addressing each meta‐atom locally with precise laser pulses and switching the PCM there. However, simultaneously controlling several different modes remains elusive. In this work, PCM‐covered aluminum split‐ring resonators (SRRs) are switched locally to tune both the electric dipole resonances as well as the magnetic dipole resonances. By selectively switching the PCM at different hotspots of the SRRs, both resonances can be tuned individually. Finally, the field enhancement in the magnetic resonance allows continuous tuning of surface‐enhanced infrared absorption of native SiO2. This work serves as a proof of principle for sophisticated resonance tuning via changes in the refractive index at the hotspots of the selected antennas enabling fine‐tuning functionalities on a meta‐atom level and allows for post‐fabrication adjustments of metasurfaces. [ABSTRACT FROM AUTHOR]

The absorption of a light wave interacting with optical transitions in the D1 line of an alkali metal atom subjected to microwave radiation that is in resonance with magnetic dipole transitions between hyperfine ground-state components, has been investigated. It is known that when scanning a longitudinal magnetic field (B || k, where k is the wavevector), one may observe a magneto-optical resonance due to the ground-state Hanle effect. In addition, the effect of double radio-optical resonance takes place because of the presence of the resonance microwave field. The joint influence of these effects on the formation of a narrow magneto-optical resonance in light wave absorption has been studied theoretically and experimentally. It has been shown analytically that the effects compete with each other and destructively act on the resonance formation. As a result, the amplitude of the resonance is small and its shape is complicated. However, in the presence of a buffer gas the pressure of which is such that the hyperfine splitting of the ground state remains spectrally unresolved, it becomes possible to observe a magneto-optical resonance with a relatively large amplitude. Experiments have been carried out with the use of a miniature glass cell (V ~ 0.1 cm3) filled with 87Rb vapor and a buffer gas argon (a pressure of about 95 Torr). In particular, the theoretically predicted resonance narrowing with increasing light field intensity has been experimentally observed. A configuration for magneto-optical resonance excitation suggested here may be applied in quantum magnetometry to measure weak permanent magnetic fields and resonance microwave fields using cells filled with alkali metal vapor. [ABSTRACT FROM AUTHOR]

Introduction: the use of magnetic resonance contrast media is a necessity. In order to obtain a more effective image, the most ideal contrast should be used to minimize adverse reactions and deposition in tissues and target organs. Due to the repeated use of these contrasts in patients with oncologic follow-up of brain tumors, contrast deposits have been observed in the brain. Objective: to study the characteristics of gadolinium-based contrast media and their use in magnetic resonance imaging. Methods: a documentary review was carried out, theoretical methods were used for the theoretical references of the subject, the interpretation of the documentary review and the progression of the information in the articles. Results: the toxicity of gadolinium-based contrast media depends on several factors and the occurrence of mild and severe adverse reactions with their use can be avoided. Conclusions: for the use of gadolinium-based contrast media, the benefit/risk ratio should be assessed, this premise should coincide with the real need for an effective diagnosis and prognosis (or both). The objective is to administer the lowest possible dose, which is related to the maximum effective enhancement time. [ABSTRACT FROM AUTHOR]

In reaction to the depletion of resources, electric vehicles are viewed as an alternate choice. Wireless power transfer (WPT) is seen as a solution to charge batteries since practical and dependable ways to charge EV batteries are crucial for increasing the use of EVs in daily life. This project involves designing and implementing a wireless charger prototype with a 60 kHz operating frequency. The drawbacks of plug-in electric vehicles (PEV) include the requirement for a cable and plug charger, the need for galvanic isolation of the on-board electronics, the bulk and high cost of this charger, and the requirement for sizable energy storage system (ESS) packs. however, by utilizing the wireless charging capability of the equipment. It offers convenience to the user, built-in electrical isolation, grid-side regulation, and on-board ESS size reduction through dynamic on-road charging. The primary objective of our project is to design and construct an antenna system that can be used for vehicles to charge electric vehicles wirelessly using resonant magnetic resonance technology. WPT use in EVs offers a clean, practical, and secure functioning. Both the primary and secondary coils are the heart of the WPT systems. The coupling coefficient of the system created by these coils ranges from 0.1 to 0.5. Resonant capacitors are required on both sides to tune them in order to transmit the rated power. The operating frequency is a crucial selection factor for all applications, and it has a significant impact on the power electronic circuit's component choices and coil size. Vehicle charging technology is developed with a resonant wireless transfer system. [ABSTRACT FROM AUTHOR]

Zero-field optically pumped magnetometers operating in the spin-exchange relaxation-free (SERF) regime have been extensively studied, and usually depend on zeroth-order parametric resonance to measure the magnetic field. However, the studies conducted on this topic lack thorough analyses and in-depth discussion of nonzero-order magnetic resonances in single-beam SERF magnetometers. In this paper, we analyzed the nonzero-order resonance, especially the first-order resonance, based on a single-beam SERF magnetometer, and discussed its various applications. A comprehensive theoretical analysis and experiments were conducted with respect to multiple functions, including nonzero finite magnetic field measurements, spin polarization measurement, and in situ coil constant calibration. The results showed that first-order resonance can be utilized for nonzerofinite magnetic field measurements, and the spin polarization of alkali-metal atoms can be determined by measuring the slowing-down factor using the resonance condition. Furthermore, acquiring the first-order resonance point at an equivalent zero pump light power through fitting offers an approach for quick and precise in situ coil constant calibration. This study contributes to the applications of SERF magnetometers in nonzero finite magnetic fields. [ABSTRACT FROM AUTHOR]

Assignment of resonances of nuclear magnetic resonance (NMR) spectra to specific atoms within a protein remains a labor-intensive and challenging task. Automation of the assignment process often remains a bottleneck in the exploitation of solution NMR spectroscopy for the study of protein structure-dynamics-function relationships. We present an approach to the assignment of backbone triple resonance spectra of proteins. A Bayesian statistical analysis of predicted and observed chemical shifts is used in conjunction with inter-spin connectivities provided by triple resonance spectroscopy to calculate a pseudo-energy potential that drives a simulated annealing search for the most optimal set of resonance assignments. Termed Bayesian Assisted Assignments by Simulated Annealing (BARASA), a C++ program implementation is tested against systems ranging in size to over 450 amino acids including examples of intrinsically disordered proteins. BARASA is fast, robust, accommodates incomplete and incorrect information, and outperforms current algorithms – especially in cases of sparse data and is sufficiently fast to allow for real-time evaluation during data acquisition. The authors present BARASA, an approach to assign backbone triple resonance spectra of proteins that augments traditional approaches with a Bayesian statistical analysis of the observed chemical shifts. The algorithm employs a simulated annealing engine to establish a consensus set of resonance assignments and is tested against systems ranging in size to over 450 amino acids including examples of intrinsically disordered proteins. [ABSTRACT FROM AUTHOR]

Nonlinear magnetic resonance is studied in an in-plane magnetized yttrium iron garnet (YIG) film. For YIG films magnetized perpendicular to the plane, the effect referred to as the foldover resonance is well known. It arises because the precession frequency increases with the deviation of the magnetization. When the field is reduced, the frequency of the precession remains resonant because the demagnetizing field decreases with the deviation of the magnetization. The signal disappears when the radio frequency pump power is insufficient to maintain a nonequilibrium state of the system. In the in-plane magnetized yttrium iron garnet film, the precession frequency decreases with an increase in the pump amplitude. Accordingly, the foldover effect arises under an increase in the field. The fundamental difference is that the precession in the latter case should be unstable with respect to the decay into spin wave modes. The deviation angles of magnetization of about 10° are reached, and the rate of decay of the uniform precession into spin waves, which depends on the deviation angle of the magnetization, is measured. This study opens up another way of achieving the magnon density corresponding to the formation of its Bose–Einstein condensate. [ABSTRACT FROM AUTHOR]

The position and width of supercritical resonance of one-electron ion in presence of a strong magnetic field are calculated. The influence of the magnetic field on the supercritical resonance parameters is investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Slice-selective refocusing pulses compromise the quantitative nature of experiments. • Relaxational signal loss may be described by a simple empirical function of pulse duration. • Two parameters control the contributions of T 1 and T 2 relaxation. • Parameter values have been determined for four common RF pulse shapes. Slice-selective refocusing pulses are powerful building blocks in contemporary magnetic resonance experiments, but their use in quantitative applications is complicated by the site-dependent signal loss they introduce. One source of this attenuation is the spin relaxation that occurs during such pulses, which causes losses that depend on the specific longitudinal and transverse relaxation time constants for a given resonance. This dependence is complicated both by any amplitude shaping of the radiofrequency pulse, and by the presence of the spatial encoding pulsed field gradient. The latter causes the net signal measured to be the weighted sum of signal contributions from a continuous range of offsets from resonance. In general, each offset will make a different contribution to the overall signal, and will be attenuated by a different mixture of longitudinal and transverse relaxation that is dictated by the different trajectories that the nuclear magnetisations take during experiments. Despite this complex behaviour, we present evidence from experiments and numerical simulations showing that in practical experimental applications a relatively simple empirical function can be used to accurately predict relaxational attenuation during slice-selective refocusing pulses. This approach may be of practical use in correcting for relaxational losses in quantitative applications of slice-selective pulse methods such as Zangger–Sterk pure shift NMR. [ABSTRACT FROM AUTHOR]

In the present work, we study the dynamics of the magnetic nanodisc coupled through a magnetoelectric coupling to a ferroelectric crystal. The model of our interest is nonlinear, and we explore the problem under different limits of weak and strong non-linearity. By applying two electric fields with different frequencies, we control the form of the confinement potential of a ferroelectric subsystem and realize different types of dynamics. We proved that the system is more sensitive to magnetoelectric coupling in the case of double-well potential. In particular, in the case of strong non-linearity, arbitrary small values of magnetoelectric coupling lead to chaotic dynamics. In essence, magnetoelectric coupling plays a role akin to the small perturbations destroying invariant tori according to the KAM theorem. We showed that bifurcations in the system are of Hopf's type. We observed the formation of magnetoelectric fractals in the system. In the limit of weak non-linearity, we studied a problem of parametric nonlinear resonance and enhancement of magnetic oscillations through magnetoelectric coupling. [ABSTRACT FROM AUTHOR]

In near‐field energy transmission, wireless power transfer based on magnetic coupling resonance is preferred. For efficient power transfer, the quality factor of magnetic coupling resonance wireless power transfer (MCR‐WPT) system should be kept at a high value, which makes the system sensitive to frequency detuning. Different from conventional approaches dealing with the problem in linear MCR‐WPT system, this paper proposes a novel MCR‐WPT system, which is based on Van der Pol nonlinear resonant circuit to address the problem of frequency detuning. A nonlinear resistor is introduced, and the nonlinear Van der Pol MCR‐WPT system is established. Based on the mathematical model and the theoretical analysis, it is found that the frequency band is broadened. To validate the performance of the proposed system, extensive simulation and experimental work are conducted. Unlike the traditional linear system, which only peaks at the resonant frequency, the results show that the output of the proposed system is still high within a certain frequency band when the operating frequency deviates from the original resonant frequency. The impact of frequency detuning caused by variation of capacitance is also studied. It can be concluded that the proposed MCR‐WPT system is effective in coping with the frequency detuning. [ABSTRACT FROM AUTHOR]

In this article, a dual-band dual-circularly polarized (CP) narrow slot antenna with stable in-band gain and reduced frequency ratio (FR) is proposed by resonating the $0.5\lambda $ -, ${\it \lambda }$ -, and $2{\it \lambda }$ -modes. For this purpose, two critical issues are significantly investigated and explored. The first effort is attempted to construct two pairs of orthogonal polarization with opposite rotation, i.e., (${\it \lambda }$ - and $0.5{\it \lambda }$ -modes) and ($0.5{\it \lambda }$ - and $2{\it \lambda }$ -modes), by properly reshaping the equivalent magnetic currents of the slot radiator. Another attempt is to reallocate these modes in proximity to each other in virtue of stub-loaded technique and ensure them to resonate in the designated sequence of ${\it \lambda }$ -, $0.5{\it {\lambda }}$ -, and $2{\it \lambda }$ -modes instead of the inherent sequence. With these improvements, the dual-CP performance can be successfully realized for our designed antenna. Finally, for experimental verification, a dual-band dual-CP slot antenna in virtue of the proposed design approach is implemented and tested. It proves that the left- and right-hand CP radiation patterns toward the ${z}$ -axis are satisfactorily obtained around 1.88 and 2.39 GHz by simultaneously employing the triple resonance, thus revealing a small FR of 1.27. Moreover, the dual operation bands hold stable in-band gains of about 2.8 and 3.5 dBic. In addition, the CP antenna still maintains the single-layer, single-fed, and single-radiator properties, which evidently confirms the validity and effectiveness of the proposed design. [ABSTRACT FROM AUTHOR]

Global and local multitrace formulations (MTFs) provide a flexible and efficient method for the modeling of scattering and transmission of time harmonic electromagnetic (EM) waves by composite structures. This contribution extends the domain of applicability of global MTFs to cases where penetrable domains, perfectly conducting domain, and perfectly conducting thin sheets are all part of the design. A novel and easy to implement resonance-free equation to model scattering by perfect conductors is introduced. A Calderón preconditioner designed to limit the number of iterations required for the solution of the discrete system is designed and studied. The accuracy, flexibility, and efficiency of the method are demonstrated on a representative range of examples. [ABSTRACT FROM AUTHOR]

The resonance property of a magnetic vortex contained within a micron-sized square Py dot was detected using an amplitude-modulated magnetic field excitation technique. We found a significant modulation of the resonant spectra as the external magnetic field changes. The Lorentzian-like spectrum changes from a peak to a dip via a transition of anti-Lorentzian-like spectra. By conducting the micromagnetic simulations, we confirmed that the transition behavior results from the unusual resistance change depending on the vortex core center position. Additionally, the power dependence of the anti-Lorentzian-like spectra revealed a fairly persistent coexistence of peak and dip. Thus, the tunable spectra suggest one way to develop an integratable radiofrequency microcircuits. [ABSTRACT FROM AUTHOR]

The recently discovered spin-active boron vacancy (V B − ) defect center in hexagonal boron nitride (hBN) has high contrast optically-detected magnetic resonance (ODMR) at room-temperature, with a spin-triplet ground-state that shows promise as a quantum sensor. Here we report temperature-dependent ODMR spectroscopy to probe spin within the orbital excited-state. Our experiments determine the excited-state spin Hamiltonian, including a room-temperature zero-field splitting of 2.1 GHz and a g-factor similar to that of the ground-state. We confirm that the resonance is associated with spin rotation in the excited-state using pulsed ODMR measurements, and we observe Zeeman-mediated level anti-crossings in both the orbital ground- and excited-state. Our observation of a single set of excited-state spin-triplet resonance from 10 to 300 K is suggestive of symmetry-lowering of the defect system from D3h to C2v. Additionally, the excited-state ODMR has strong temperature dependence of both contrast and transverse anisotropy splitting, enabling promising avenues for quantum sensing. The negatively charged boron vacancy in hBN shows promise as a quantum sensor, but, until recently, the focus has been on its ground-state properties. Here, the authors report temperature-dependent spin-resonance optical spectroscopy of the orbital excited state. [ABSTRACT FROM AUTHOR]

This paper describes the design and analysis of the tri-band metamaterial band-stop filter for terahertz applications. The design consists of a structured gold metallic patch over a flexible polyimide substrate. The thicknesses of the substrate and the metallic patch are 125 and 1 μ m , respectively. The simulation results reveal that the designed structure resonates at three frequencies: f 1 = 0.6 THz, f 2 = 1.4 THz and f 3 = 2.4 THz. The proposed structure has polarisation-insensitive and angle-resolved transmission characteristics. The structure has 200 GHz and 800 GHz bandwidths at f 1 and f 2 . This proves that the proposed design will be useful for broadband terahertz applications. The multiband resonances have been confirmed and analysed using the field and surface current distributions. These multiband resonances were due to the combination of electric dipolar, quad polar and magnetic dipolar resonance behaviour of the patterned metallic structure. [ABSTRACT FROM AUTHOR]

The toroidal dipole is a localized electromagnetic excitation induced by a reversely distributed circulating current. The magnetic fields with opposite directions are connected end to end to form a closed circular magnetic field, and a toroidal dipole with non-radiative electric field characteristics is obtained. However, active manipulation of the toroidal resonance has remained largely unexplored due to the scarcity of compact tunable elements so far. Here, we propose a planar terahertz metamaterial composed of an asymmetric metallic double splits ring resonator, which can excite a toroidal dipole resonance. To active control the toroidal dipole resonance, the monolayer graphene is integrated with the metamaterial. By changing Fermi energy of graphene, the transmission amplitude of the toroidal dipole resonance is actively modulated and finally switched into a electric resonance or magnetic resonance. Therefore, switching between the non-radiation and the high-radiation, as well as active modulation of the toroidal dipole have potential application prospects in the design of filters, high-sensitivity sensors, and modulators. [ABSTRACT FROM AUTHOR]

We study optical detection of magnetic resonance of a ferrimagnetic sphere resonator, which is strongly coupled to a microwave loop gap resonator. Optical fibers are employed for coupling the sphere resonator with light in the telecom band. We find that magnetic resonance can be optically detected near the region of anti-crossing between the loop gap and the ferrimagnetic resonances. The detection bandwidth is found to be limited by a ferrimagnetic damping rate. [ABSTRACT FROM AUTHOR]

A magnetoelastic resonance sensor of composition Fe73Cr5Si10B12 is used to monitor the precipitation reaction of calcium oxalate (CaC2O4) by measuring the changes in its resonance frequency, caused by the mass increase on its surface, during the precipitation process. Numerical fittings of the resonance curves were performed in order to improve the detection resolution. With respect to previous works on the monitoring of this precipitation reaction, this work explores the limit of detection of the technique, and the ability of the numerical fittings to improve the quality of the signals measured and the parameters that are extracted from them. For this purpose, the monitoring of the precipitation reactions when using reagents (oxalic acid and calcium chloride) of concentrations 1, 3, 5, and 10 mM were studied. The results show that the sensor is capable of tracking the precipitation reaction of solutions of concentration as low as 1 mM (the solubility limit of calcium oxalate is about 0.1 mM), with the sensor being able to resolve a mass of precipitate of $2~\mu \text{g}$. [ABSTRACT FROM AUTHOR]

The resonant properties of thin dielectric rings excited by displacement currents in the case of the sliding incidence of a plane electromagnetic wave in the microwave frequency range on the ring plane are studied. Such a circuit with an azimuthal displacement current forms a resonant dielectric magnetic dipole. The basic resonance excited by the magnetic field in the near zone of the indicated dipole is calculated and measured. The inversion of the magnetic induction flux and the appearance of negative magnetic susceptibility in the resonance region of a dielectric magnetic dipole are shown. The distribution of the magnetic field near a dielectric ring near the resonant frequency is experimentally measured. [ABSTRACT FROM AUTHOR]

In this paper, a broadband polarization conversion metasurface in microwave regime based on cross-shaped resonators was proposed. The simulated results show that the converter can convert linear polarization wave into its cross-polarization wave, 2 dB bandwidth is 11.5–21.8 GHz, and the Polarization Conversion Ratio is greater than 96% in this range. The simulated surface current distributions show that there are three plasmon resonances generated by magnetic resonances and electric resonance, resulting in broadband cross-polarized reflections, and electromagnetic composite resonances in the same direction will inhibit cross-polarization reflection. The proposed converter presents polarization selectivity, which can only convert the y- and x-polarized waves completely. When the incident angles reach 40°, the converter also shows high-efficiency polarization conversion. The experimental results are highly consistent with the simulation ones. This work may have some potential application in polarization-controlled devices, stealth surfaces, antennas and etc. [ABSTRACT FROM AUTHOR]

Magnetic resonant wireless power transfer (WPT) is an emerging technology that may create new applications for wireless power charging. However, low efficiency resulting from resonant frequency drift is a main obstructing factor for promoting this technology. In this paper, the system efficiency and input impedance are obtained by solving the system equivalent equations and based on that a method of adjusting the operating frequency and load resistor is proposed. When resonant frequency drift occurs, the WPT system can now operate at quasi-resonant state and the efficiency can be improved by using the proposed method. The WPT system via magnetic resonance coupling is designed. Simulation and experimental results validating the proposed method are given. [ABSTRACT FROM AUTHOR]

Cold atom experiments commonly use broad magnetic Feshbach resonances to manipulate the interaction between atoms. In order to induce quantum dynamics by a change in the interaction strength, rapid (∼μs) magnetic field changes over several tens of Gauss are required. Here, we present a compact design of a coil and its control circuit for a change in the magnetic field up to 36 G in 3 µs. The setup comprises two concentric solenoids with minimal space requirements, which can be readily added to existing apparatuses. This design makes the observation of non-equilibrium physics with broad Feshbach resonances accessible. [ABSTRACT FROM AUTHOR]

This research paper presents the design of a wireless power transfer (WPT) circuit integrated with magnetic resonance coupling (MRC) and harvested radio frequency (RF) energy to wirelessly charge the battery of a mobile device. A capacitor (100 µF, 16 V) in the RF energy harvesting circuit stored the converted power, and the accumulated voltage stored in the capacitor was 9.46 V. The foundation of the proposed WPT prototype circuit included two coils (28 AWG)—a transmitter coil, and a receiver coil. The transmitter coil was energized by the alternating current (AC), which produced a magnetic field, which in turn induced a current in the receiver coil. The harvested RF energy (9.46 V) was converted into AC, which energized the transmitter coil and generated a magnetic field. The electronics in the receiver coil then converted the AC into direct current (DC), which became usable power to charge the battery of a mobile device. The experimental setup based on mathematical modeling and simulation displayed successful charging capabilities of MRC, with the alternate power source being the harvested RF energy. Mathematical formulae were applied to calculate the amount of power generated from the prototype circuit. LTSpice simulation software was applied to demonstrate the behavior of the different components in the circuit layout for effective WPT transfer. [ABSTRACT FROM AUTHOR]

Achieving perfect reflection with minimal loss and high efficiency is possible through the utilization of all-dielectric metamaterials, capitalizing on Mie resonance in materials with high permittivity. In this study, we introduce a novel approach to create a tunable perfect reflector operating within the near-infrared spectrum. This reflector is constructed using an all-dielectric metamaterial consisting of a SiO 2 substrate and a periodic array of Si cuboids. Through precise adjustments in size and period, we demonstrate the attainment of near-perfect reflection across the near-infrared band. Notably, the reflector exhibits a bandwidth of 350.5 nm and maintains an average reflection exceeding 99 % over the spectral range from 1444.5 nm to 1795.0 nm. By customizing the electric and magnetic resonances throughout the near-infrared spectrum, our design offers adaptability to fulfill specific reflection bandwidth requirements. The tunable perfect reflector shows great potential for applications in various fields, including filtering, sensing, and optical communication, offering enhanced performance and versatility. [Display omitted] • A novel approach has been proposed to create a tunable perfect reflector operating within the near-infrared spectrum. • The reflector exhibits a bandwidth of 350.5 nm and maintains an average reflection exceeding 99 % over the spectral range from 1444.5 nm to 1795.0 nm. • This reflector is constructed using an all-dielectric metamaterial consisting of a SiO 2 substrate and a periodic array of Si cuboids. [ABSTRACT FROM AUTHOR]

• The vertical resonator achieves the stability of the bandwidth between two frequencies and the high-bandwidth phase regulation by exciting the dual resonance mode of the magnetic dipole and the quadrupole Resonance, and the metasurface satisfies the 3-Bit encoding requirements of LP and CP by regulating the single structural parameters. • The multi-stage vortex beams was excited and separated using the coded convolutional addition method over a wide frequency range of LP and CP. The large angle deflection and scanning of the vortex beam can be effectively achieved by regulating the angle and frequency of the incident wave. • This design method and structure has multitype polarization wave universality and ultra-wide working bandwidth. Meanwhile, the method can be effectively applied to optical band and microwave band. A metasurface design scheme is proposed based on reflective double vertical U-shaped resonators. Compared to planar resonators with the same parameters, vertical meta -atom can excite magnetic dipole resonance and quaternary resonance respectively at low and high frequency to achieve stable wideband phase shift and unique free regulation. Vertical meta -atoms can be applied as 3-bit coding elements in linearly polarized (LP) and circularly polarized (CP) states with bandwidths of 0.7–1.1 THZ and 0.55–1.5 THZ, respectively. At the same time, as a half-wave plate, the deflection conversion rate is 95%, the relative bandwidth is 69%, and the operating Angle is 80°. In order to verify the application capability of the designed meta -atom, the excitation and separation of multi-stage vortex beams are performed in the wide frequency range of LP and CP using the coded convolutional addition method. The designed meta -atom only needs to regulate a single structural parameter to fully satisfy the requirements of 3-Bit broadband coding under LP and CP incidence, so it has multi-type polarization wave universality and ultra-wide working bandwidth. Meanwhile, the method can be effectively applied to optical band and microwave band. [ABSTRACT FROM AUTHOR]

We present a theoretical study of the optical-radio-frequency (rf) double resonance on hyperfine ground states of alkali-metal atoms in the geophysical magnetic-field range, in which resonance circularly polarized laser light is used in the optical pumping and detection processes. The analytical expressions of the rf resonance signals corresponding to two ground states are obtained based on atomic multipole moments, where the alignment effect is considered and that is responsible for the resonance shape and linewidth especially when the optical power is relatively strong. In addition, we also obtain the analytical expressions of the linewidths of two separated resonance peaks and one presenting the competition process of the optical pumping, rf field and spin-exchange collision. Two different types of light narrowing phenomena are investigated by comparing the longitudinal relaxation rates of atomic multipole moments for two ground states. Applied to rubidium and cesium atoms, we show a particularly close agreement of our analytical results with more elaborate calculations using density-matrix theory. Our theoretical model is relevant for optimizing the sensitivity of magnetometers. [ABSTRACT FROM AUTHOR]

We study the angle dependence of the spin wave resonance spectra in FeNi–MgO granular films fabricated by magnetron sputtering, using ferromagnetic resonance technology. Seven Portis-type spin resonances with the same magnetic field spacing are observed when the magnetic field is perpendicular to the film. By varying the field angle θH, we find that there are at least two resonance modes at θH = 14°, indicating that the critical angle θc of the ferromagnetic resonance mode is in the range of 14°–15°. Furthermore, we obtained the exchange stiffness constant and distortion parameter through the surface inhomogeneity model and the volume inhomogeneity model. Moreover, in order to figure out the types of spin wave, we also investigate the dependence of spin wave resonance spectra on temperature, which reveals an excitation of the perpendicular spin standing wave. [ABSTRACT FROM AUTHOR]

Resonant wireless power transfer (RWPT) allows for efficient transfer of electrical energy over an air gap, by optimally tuning a receiver resonator. Next to transferring electrical energy to supply or charge a device, previous work demonstrated that the induced current in receiver resonators can be directly applied to exert mechanical torque on a rotor axle. The peak torque however only occurs when both receiver coils are uncoupled because the magnetic coupling of two resonators strongly affects their current. In this work, we investigate the effect of intentionally detuning the resonators coils in a RWPT motoring system on its torque generation capability. Overall, the detuned system is more robust, and significant gains in average (72.1%), and maximum torque (40.6%) are obtained. [ABSTRACT FROM AUTHOR]

The magnetic field dependence of the amplitudes of Shubnikov–de Haas oscillations in GaAs/AlGaAs heterostructure samples with a two-dimensional electron system irradiated by microwave radiation in the range of 130–170 GHz has been studied. Two features of the radiation-induced suppression of amplitudes of oscillations having a field-resonance character have been revealed. One of the resonances appears in a magnetic field corresponding to the second harmonic of the cyclotron resonance, whereas the dependence of the existence, position, and amplitude of the second resonance on the radiation frequency is more complex. The detected resonance absorption of radiation at the second harmonic is apparently responsible for an anomalous peak of the magnetoresistance recently observed near this harmonic. The detected resonances can be explained by the excitation of standing magnetoplasma waves in a confined sample with the same the wavenumber but corresponding to different regions of their dispersion relation: an almost dispersionless region of the Bernstein mode and a cyclotron magnetoplasma mode. [ABSTRACT FROM AUTHOR]

Four resonance compensation topologies equivalent circuit models for magnetic field coupling resonance wireless power transfer system (primary side series and secondary side series type, primary side series secondary side parallel type, primary side parallel secondary side series type and primary side parallel secondary side parallel type) was constructed. The efficiency characteristics of magnetic field coupling resonance wireless power transfer system was analyzed. The influence of coupling coefficient and quality factor on system efficiency was studied. The simulation results showed that the secondary side resonance compensation topology had a greater impact on the system efficiency, and the system efficiency was more sensitive to changes in the coupling coefficient and quality factors. Compared with the secondary side using the series compensation topology, the system had a wider range of high transfer efficiency when the secondary side used the parallel compensation topology. The experimental results verified the correctness of the simulation results. [ABSTRACT FROM AUTHOR]

The coupling of two nonidentical magnetic nanodisks, i.e., with different vortex gyrotropic frequencies, is studied. From the analytical approach, the interactions between the nanodisks along x and y directions (the coupling integrals) were obtained as a function of distance. From the numerical solution of Thiele's equation, we derived the eigenfrequencies of the vortex cores as a function of distance. The motion of the two vortex cores and, consequently, the time dependence of the total magnetization M(t) were derived both using Thiele's equation and by micromagnetic simulation. From M(t), a recently developed method, the magnetic vortex echoes, analogous to the Nuclear Magnetic Resonance spin echoes, was used to compute the distance dependence of the magnetic coupling strength. The results of the two approaches differ by approximately 10%; using one single term, a dependence with distance found is broadly in agreement with studies employing other techniques. [ABSTRACT FROM AUTHOR]