Strong Magnetic Field Gradients Research Articles

Properties of Quiet Magnetotail Plasma Sheet at Lunar Distances

AbstractThe Earth's magnetotail at lunar distances (R ≈ 60 RE) serves as a unique laboratory to study plasma dynamics in a weak, highly fluctuating magnetic field with a strong magnetic field gradient. In particular, studies of the of quiet‐time plasma in the lunar‐distant magnetotail can inform us about plasma entry to the magnetosphere and sources of magnetospheric plasma populations. We use the data collected by the two lunar‐orbiting Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) spacecraft during its 2013–2019 magnetotail traversals to infer the average thermodynamic and spectral properties of plasma populations in the quiet‐time (i.e., low geomagnetic activity and absence of fast plasma flows) magnetotail at lunar distances. We found that plasma temperature and density in the quiet‐time magnetotail at R ≈ 60 RE are organized by the magnetic field. Three distinct regions with plasma β ≫ 1, β ∼ 1, and β ≪ 1, the central plasma sheet (CPS), outer plasma sheet (OPS), and lobes are sampled. We found that temperatures and energy spectra of ion populations in CPS, OPS, and lobes regimes are different: the hotter CPS temperatures scale with the kinetic energy of solar wind protons; cold OPS/lobe ions are, likely, of ionospheric origin. The ion and electron particle spectra in CPS, OPS, and lobes are nonthermal and reasonably well fitted by the Kappa function, with κ exponent varying between 2.5 and 3.5.

Atomic gravimeter robust to environmental effects

Atomic accelerometers and gravimeters are usually based on freely falling atoms in atomic fountains, which not only limits their size but also their robustness to environmental factors, such as tilts, magnetic fields, and vibrations. Such limitations have precluded their broad adoption in the field, for geophysics, geology, and inertial navigation. More recently, atom interferometers based on holding atoms in an optical lattice have been developed. Such gravimeters also suppress the influence of vibrations in the frequency range of ∼1 Hz and above by several orders of magnitude relative to conventional atomic gravimeters. Here, we show that such interferometers are robust to tilts of more than 8 mrad with respect to the vertical and can suppress the effect of even strong environmental magnetic fields and field gradients by using atoms in the F=3, 4 hyperfine ground states as co-magnetometers, potentially eliminating the need for shielding. We demonstrate gravimeter sensitivity of 0.7 mGal/Hz (1 mGal = 10 μm/s2) in a compact geometry where atoms only travel over millimeters of space.

Transverse relaxation measurements for moving samples in the presence of strong magnetic field gradients

Nuclear Magnetic Resonance (NMR) is one of the primary techniques used in the oil industry for logging operations and in the laboratory environment to study rock formations due to its reliability in offering a reliable estimation of oil well productivity. Two types of well-logging operations exist, Wireline Logging and Logging While Drilling (LWD). Wireline Logging involves NMR measurements taken under static conditions. In contrast, LWD involves measurements taken during the drilling process while the tool is in motion, translating, rotating, and vibrating relative to the formation. To understand the behavior of NMR signals measured under LWD conditions on a laboratory scale, we developed a setup that includes a single-sided magnet, rf probes, and a mechanical system that emulates a relative sinusoidal motion between the sample and the applied magnetic field. Four representative rock samples were selected according to their relaxation times, which were short, intermediate, and long compared to the oscillation period of the LWD simulator: three sandstone, Fontainebleau, Berea Sandstone, and Portland Red, and one carbonate, Indiana Limestone. The results show that even with the modifications observed in the relaxation times distribution, which could lead to misinterpreting the geological formation parameters, the total porosity remains unaffected and independent of the sample motion during the NMR measurements, even under severe conditions and using the standard procedures of the data processing.

Transient rising of oxygen bubbles in a fast varying gravity

We report experiments on the transient motion of an oxygen bubble rising in liquid oxygen in a fast varying magneto-gravitational acceleration. In the set-up, a strong magnetic field gradient is applied, which creates in bulk oxygen a body force opposed to its weight. When this gravity compensation is suddenly suppressed, the resulting apparent gravity increases within a fraction of a second from 0 g0 to 0.4 g0 (where g0 is the terrestrial gravitational acceleration). Oxygen bubbles of diameters ranging from 6 mm to 18 mm rise rapidly in the liquid by buoyancy, for values of Galilei and Bond numbers rarely reached with common fluids in terrestrial gravity. The shape of the bubble interface is initially ellipsoidal and evolves toward more complicated shapes during the motion. The time-dependent rising velocity of the bubble is measured during the fast variation of gravity. A comparison of the transient bubble dynamics with classical results obtained in a constant gravity environment enables the time scale of the gravity variation to be precisely quantified.

Parametric investigation of azimuthal instabilities and electron transport in a radial-azimuthal E × B plasma configuration

Partially magnetized low-temperature plasmas (LTP) in an E × B configuration, where the applied magnetic field is perpendicular to the self-consistent electric field, have become increasingly relevant in industrial applications. Hall thrusters, a type of electrostatic plasma propulsion, are one of the main LTP technologies whose advancement is hindered by the not-fully-understood underlying physics of operation, particularly, with respect to the plasma instabilities and the associated electron cross field transport. The development of Hall thrusters with unconventional magnetic field topologies has imposed further questions regarding the instabilities' characteristics and the electrons' dynamics in these modern cross field configurations. Accordingly, we present in this effort a detailed parametric study of the influence of three factors on the plasma processes in the radial-azimuthal coordinates of a Hall thruster, namely, the magnetic field gradient, secondary electron emission, and plasma number density. The studies are carried out using the reduced-order particle-in-cell code developed by the authors. The setup of the radial-azimuthal simulations largely follows a well-defined benchmark case from the literature in which the magnetic field is oriented along the radius, and a constant axial electric field is applied perpendicular to the simulation plane. The salient finding from our investigations is that, in the studied cases corresponding to elevated plasma densities, a long-wavelength azimuthal mode with the frequency of about 1 MHz is developed. Moreover, in the presence of strong magnetic field gradients, this mode results from an inverse energy cascade and induces a significant electron cross field transport as well as a notable heating of the ions.

Correlation between diffusion tensor indices and fascicular morphometric parameters of peripheral nerve.

Introduction: Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) technique that measures the anisotropy of water diffusion. Clinical magnetic resonance imaging scanners enable visualization of the structural integrity of larger axonal bundles in the central nervous system and smaller structures like peripheral nerves; however, their resolution for the depiction of nerve fascicular morphology is limited. Accordingly, high-field strength MRI and strong magnetic field gradients are needed to depict the fascicular pattern. The study aimed to quantify diffusion tensor indices with high-field strength MRI within different anatomical compartments of the median nerve and determine if they correlate with nerve structure at the fascicular level. Methods: Three-dimensional pulsed gradient spin-echo (PGSE) imaging sequence in 19 different gradient directions and b value 1,150s/mm2 was performed on a 9.4T wide-bore vertical superconducting magnet. Nine-millimeter-long segments of five median nerve samples were obtained from fresh cadavers and acquired in sixteen 0.625mm thick slices. Each nerve sample had the fascicles, perineurium, and interfascicular epineurium segmented. The diffusion tensor was calculated from the region-average diffusion-weighted signals for all diffusion gradient directions. Subsequently, correlations between diffusion tensor indices of segmentations and nerve structure at the fascicular level (number of fascicles, fascicular ratio, and cross-sectional area of fascicles or nerve) were assessed. The acquired diffusion tensor imaging data was employed for display with trajectories and diffusion ellipsoids. Results: The nerve fascicles proved to be the most anisotropic nerve compartment with fractional anisotropy 0.44 ± 0.05. In the interfascicular epineurium, the diffusion was more prominent in orthogonal directions with fractional anisotropy 0.13 ± 0.02. Diffusion tensor indices within the fascicles and perineurium differed significantly between the subjects (p < 0.0001); however, there were no differences within the interfascicular epineurium (p ≥ 0.37). There were no correlations between diffusion tensor indices and nerve structure at the fascicular level (p ≥ 0.29). Conclusion: High-field strength MRI enabled the depiction of the anisotropic diffusion within the fascicles and perineurium. Diffusion tensor indices of the peripheral nerve did not correlate with nerve structure at the fascicular level. Future studies should investigate the relationship between diffusion tensor indices at the fascicular level and axon- and myelin-related parameters.

Formation of the Mg ii h and k Polarization Profiles in a Solar Plage Model and Their Suitability to Infer Magnetic Fields

The Mg ii h and k lines are among the strongest in the near-ultraviolet solar spectrum and their line core originates in the upper chromosphere, just below the transition region. Consequently, they have become one of the main targets for investigating the magnetism of the upper solar atmosphere. The recent Chromospheric Layer Spectropolarimeter (CLASP2) mission obtained unprecedented spectropolarimetric data on these lines in an active region plage, which have already been used to infer the longitudinal component of the magnetic field by applying the weak-field approximation. In this paper, we aim at improving our understanding of the diagnostic capabilities of these lines by studying the emergent Stokes profiles resulting from radiative transfer calculations in a radiative magnetohydrodynamic time-dependent model representative of a solar plage. To this end, we create a synthetic observation with temporal and spatial resolutions similar to those of CLASP2. We find strong asymmetries in the synthetic profiles of circular polarization, which considerably complicate the application of the weak-field approximation. We demonstrate that the selective application of the weak-field approximation to fit different spectral regions in the profile allows us to retrieve information about the longitudinal component of the magnetic field in different regions of the model atmosphere, even when the circular polarization profiles are not antisymmetric and are formed in the presence of strong velocity and magnetic field gradients.

Energetic electron scattering by kinetic Alfvén waves at strong magnetic field gradients of dipolarization front

Energetic electron scattering and precipitation from the Earth's plasma sheet to the ionosphere is an important contributor to magnetosphere–ionosphere coupling. In this study, we investigate the role of one of the most intense wave emissions, kinetic Alfvén waves (KAWs), in energetic electron scattering. We have evaluated the effect of KAWs on energetic electrons within a curved magnetic field configuration exhibiting sharp cross field gradients. The magnetic field in Earth's magnetotail plasma sheet with an embedded dipolarization front is used as a working example. Taking into account electron bounce motion and perpendicular guiding-center drifts, we have shown that electrons with energies of tens to hundreds of keV can be scattered by KAWs in pitch angle and momentum through Doppler-shifted Landau resonance near the magnetic equator. The bounce-averaged pitch-angle diffusion coefficients for near-loss-cone (∼2°) electrons are on the order of 10–7–10–6 rad2/s for a characteristic KAW amplitude of 1 mV/m and approach the strong diffusion limit of ∼10–4 rad2/s for amplitudes of greater than 10 mV/m. These results suggest that under such ambient conditions, KAWs can pitch-angle scatter energetic electron population into the loss cone. In Earth's plasma sheet, this scattering is, thus, very likely to cause significant precipitation during active times. The diffusion coefficients of energetic electrons at large pitch angles (∼45°–∼80°) are more than two orders of magnitude larger than those of electrons near the loss cone, suggesting that KAWs contribute to isotropization of anisotropic electrons due to adiabatic heating should they drift into the vicinity of the magnetic field gradient.

Electrical Optimization Method Based on a Novel Arrangement of the Magnetic Navigation System with Gradient and Uniform Saddle Coils.

The magnetic navigation system (MNS) with gradient and uniform saddle coils is an effective system for manipulating various medical magnetic robots because of its compact structure and the uniformity of its magnetic field and field gradient. Since each coil of the MNS was geometrically optimized to generate strong uniform magnetic field or field gradient, it is considered that no special optimization is required for the MNS. However, its electrical characteristics can be still optimized to utilize the maximum power of a power supply unit with improved operating time and a stronger time-varying magnetic field. Furthermore, the conventional arrangement of the coils limits the maximum three-dimensional (3D) rotating magnetic field. In this paper, we propose an electrical optimization method based on a novel arrangement of the MNS. We introduce the objective functions, constraints, and design variables of the MNS considering electrical characteristics such as resistance, current density, and inductance. Then, we design an MNS using an optimization algorithm and compare it with the conventional MNS; the proposed MNS generates a magnetic field or field gradient 22% stronger on average than that of the conventional MNS with a sevenfold longer operating time limit, and the maximum three-dimensional rotating magnetic field is improved by 42%. We also demonstrate that the unclogging performance of the helical robot improves by 54% with the constructed MNS.

Rapid ground-state cooling of a solid-state nanoparticle assisted by a magnetic-field gradient

Cooling a solid-state nanoparticle, as a significant prerequisite of the mesoscale quantum sensing, is experimentally challenging. Here we propose an efficient cooling scheme assisted by a strong magnetic-field gradient to cool a nanoparticle down to the ground state of the vibrational degrees of freedom. By combining the Zeeman effect with quantum interference effect, the scheme can accomplish the precooling of the nanoparticle from room temperature to the Doppler cooling limit in several seconds, and can then further cool the precooled nanoparticle to the vibrational ground state within milliseconds. We specify the scheme by exemplifying the nanocrystal of diamond nitrogen-vacancy center suspended in an electromagnetic potential, indicating that this cooling scheme can accomplish the ground-state cooling from room temperature within a few seconds under the condition of currently available techniques. Our work lays a foundation for further three-dimensional cooling of suspended nanoparticles and also for realizing quantum sensing using mesoscopic particles in the future.

Formation of two-ion crystals by injection from a Paul-trap source into a high-magnetic-field Penning trap

Two-ion crystals constitute a platform for investigations of quantum nature that can be extended to any ion species or charged particle provided one of the ions in the crystal can be directly laser-cooled and manipulated with laser radiation. This paper presents the formation of two-ion crystals for quantum metrology in a 7-tesla open-ring Penning trap. $^{40}$Ca$^+$ ions are produced either internally by photoionization or externally in a (Paul-trap) source, transported through the strong magnetic field gradient of the superconducting solenoid, and captured in-flight with a mean kinetic energy of a few electronvolts with respect to the minimum of the Penning-trap potential well. Laser cooling of the two-ion crystal in a strong magnetic field towards reaching the quantum regime is also presented with particular emphasis on the cooling of the radial modes.

Electron Resonant Interaction With Whistler Waves Around Foreshock Transients and the Bow Shock Behind the Terminator

AbstractInvestigation of electron energization at (and around) the Earth's bow shock is critical to our understanding of space weather and astrophysical phenomena. The traditional adiabatic mechanisms for such energization compete with transient wave‐particle interactions there. One of the most intense wave modes resonating with electrons is the high‐frequency whistler mode, which is widely observed at (and around) the Earth's bow shock. Here, we examine these interactions in the context of the strong magnetic field gradients often found near the bow shock and at foreshock transients. Using THEMIS and ARTEMIS wave measurements, we quantify the nonlinear effects of resonant interactions between ≥100 eV electrons and intense coherent whistler waves. Such nonlinear interactions include the electron phase trapping by waves. As a result, the trapped electrons gain an energy up to several hundreds of eV. We estimate the main characteristics of the proposed acceleration mechanism and discuss its applicability to realistic plasma and magnetic field distributions.

Dynamics of Cations around DNA and Protein as Revealed by 23Na Diffusion NMR Spectroscopy

Counterions are vital for the structure and function of biomolecules. However, the behavior of counterions remains elusive due to the difficulty in characterizing mobile ions. Here, we demonstrate that the dynamics of cations around biological macromolecules can be revealed by 23Na diffusion nuclear magnetic resonance (NMR) spectroscopy. NMR probe hardware capable of generating strong magnetic field gradients enables 23Na NMR-based diffusion measurements for Na+ ions in solutions of biological macromolecules and their complexes. The dynamic properties of Na+ ions interacting with the macromolecules can be investigated using apparent 23Na diffusion coefficients measured under various conditions. Our diffusion data clearly show that Na+ ions retain high mobility within the ion atmosphere around DNA. The 23Na diffusion NMR method also permits direct observation of the release of Na+ ions from nucleic acids upon protein–nucleic acid association. The entropy change due to the ion release can be estimated from the diffusion data.

Improving the sensitivity of spin-echo fMRI at 3T by highly accelerated acquisitions.

Spin-echo (SE) functional MRI (fMRI) can be highly advantageous compared to gradient-echo (GE) fMRI with respect to magnetic field-inhomogeneity artifacts. However, at 3T, the majority of blood oxygenation level-dependent (BOLD) fMRI experiments are performed using -weighted GE sequences because of their superior sensitivity compared to SE-fMRI. The presented SE implementation of a highly accelerated GE pulse sequence therefore aims to improve the sensitivity of SE-fMRI while profiting from a reduction of susceptibility-induced signal dropout. Spin-echo MR encephalography (SE-MREG) is compared with the more conventionally used spin-echo echo-planar imaging (SE-EPI) and spin-echo simultaneous multislice (SE-SMS) at 3T in terms of capability to detect neuronal activations and resting-state functional connectivity. For activation analysis, healthy subjects underwent consecutive SE-MREG (pulse repetition time [TR] = 0.25 seconds), SE-SMS (TR = 1.3 seconds), and SE-EPI (TR = 4.4 seconds) scans in pseudorandomized order applied to a visual block design paradigm for generation of t-statistics maps. For the investigation of functional connectivity, additional resting-state data were acquired for 5 minutes and a seed-based correlation analysis using Stanford's FIND (Functional Imaging in Neuropsychiatric Disorders) atlas was performed. The increased sampling rate of SE-MREG relative to SE-SMS and SE-EPI improves the sensitivity to detect BOLD activation by 33% and 54%, respectively, and increases the capability to extract resting-state networks. Compared with a brain region that is not affected by magnetic field inhomogeneities, SE-MREG shows 2.5 times higher relative signal strength than GE-MREG in mesial temporal structures. SE-MREG offers a viable possibility for whole-brain fMRI with consideration of brain regions that are affected by strong susceptibility-induced magnetic field gradients.

Rotating spin-1/2 Bose–Einstein condensates in a gradient magnetic field with spin–orbit coupling

We study the ground-state phases of two-dimensional rotating spin–orbit coupled spin-1/2 Bose–Einstein condensates (BECs) in a gradient magnetic field. The competition between gradient magnetic field, spin–orbit coupling and rotation leads to a variety of ground-state phase structures. In the weakly rotation regime, as the increase of gradient magnetic field strength, the BECs experiences a phase transition from the unstable phase to the single vortex-line phase. The unstable phase presents the vortex lines structures along the off-diagonal direction. With magnetic field gradient strength increasing, the number of vortex lines changes accordingly. As the magnetic field gradient strength increases further, the single vortex-line phase with a single vortex line along the diagonal direction is formed. The phase diagram shows that the boundary between the two phases is linear with the relative repulsion λ ≥ 1 and is nonlinear with λ < 1. In the relatively strong rotation regime, in addition to the unstable phase and the single vortex-line phase, the vortex-ring phase is formed for the strong magnetic field gradient and rapid rotation. The vortex-ring phase shows the giant and hidden vortex structures at the center of ring. The strong magnetic field gradient makes the number of the vortices around the ring unchanged.

Robust energy-selective tunneling readout of singlet-triplet qubits under large magnetic field gradient

Fast and high-fidelity quantum state detection is essential for building robust spin-based quantum information processing platforms in semiconductors. The Pauli spin blockade (PSB)-based spin-to-charge conversion and its variants are widely used for the spin state discrimination of two-electron singlet–triplet (ST0) qubits; however, the single-shot measurement fidelity is limited by either the low signal contrast, or the short lifetime of the triplet state at the PSB energy detuning, especially due to strong mixing with singlet states at large magnetic field gradients. Ultimately, the limited single-shot measurement fidelity leads to low visibility of quantum operations. Here, we demonstrate an alternative method to achieve spin-to-charge conversion of ST0 qubit states using energy-selective tunneling between doubly occupied quantum dots (QDs) and electron reservoirs. We demonstrate a single-shot measurement fidelity of 90% and an S–T0 oscillation visibility of 81% at a field gradient of 100 mT (~500 MHz h (g*·μB)−1); this allows single-shot readout with full electron charge signal contrast and, at the same time, long and tunable measurement time with negligible effect of relaxation even at strong magnetic field gradients. Using an rf-sensor positioned opposite to the QD array, we apply this method to two ST0 qubits and show high-visibility readout of two individual single-qubit gate operations is possible with a single rf single-electron transistor sensor. We expect our measurement scheme for two-electron spin states can be applied to various hosting materials and provides a simplified and complementary route for multiple qubit state detection with high accuracy in QD-based quantum computing platforms.

Single-Sided Magnetic Particle Imaging Device with Field-Free-Line Geometry for in-vivo Imaging Applications.

Magnetic Particle Imaging (MPI) has shown great promise to surpass existing in vivo imaging modalities in some clinical applications. However, one of the challenges to MPI being translated into clinical practice has been the ability to scale up the selection field coils to surround a human body while being able to generate and drive a sufficiently strong magnetic field gradient. These requirements impose safety concerns as well as prohibitively high-power consumption in devices with large cylindrical volume. Therefore, we consider an alternative approach such as a single-sided topology, in which all the hardware is located on one side of the imaging volume accommodating larger subjects. Moreover, different from the previously implemented field-free point single-sided scanners, we realized a field-free line geometry providing, in principle, factor of ten higher signal and benefiting from a more robust back-projection image reconstruction technique. In this work, we present and characterize a first prototype of a single-sided MPI device with field-free-line geometry suited for in-vivo imaging of small animals as well as regions of interest in humans.

Real-time measurement of diffusion exchange rate in biological tissue

Diffusion exchange spectroscopy (DEXSY) provides a means to isolate the signal attenuation associated with exchange from other sources of signal loss. With the total diffusion weighting b1+b2=bs held constant, DEXSY signals acquired with b1=0 or b2=0 have no exchange weighting, while a DEXSY signal acquired with b1=b2 has maximal exchange weighting. The exchange rate can be estimated by fitting a diffusion exchange model to signals acquired with variable mixing times. Conventionally, acquired signals are normalized by a signal with b1=0 and b2=0 to remove the decay due to spin–lattice relaxation. Instead, division by a signal with equal bs but b1=0 or b2=0 reduces spin–lattice relaxation weighting of the apparent exchange rate (AXR). Furthermore, apparent diffusion-weighted R1 relaxation rates can be estimated from non-exchange-weighted DEXSY signals. Estimated R1 values are utilized to remove signal decay due to spin–lattice relaxation from exchange-weighted signals, permitting a more precise estimate of AXR with less data. Data reduction methods are proposed and tested with regards to statistical accuracy and precision of AXR estimates on simulated and experimental data. Simulations show that the methods are capable of accurately measuring the ground-truth exchange rate. The methods remain accurate even when the assumption that DEXSY signals attenuate with b is violated, as occurs for restricted diffusion. Experimental data was collected from fixed neonatal mouse spinal cord samples at 25 and 7°C using the strong static magnetic field gradient produced by a single-sided permanent magnet (i.e., an NMR MOUSE). The most rapid method for exchange measurements requires only five data points (an 80 s experiment as implemented) and achieves a similar level of accuracy and precision to the baseline method using 44 data points. This represents a significant improvement in acquisition speed, overcoming a barrier which has limited the use of DEXSY on living specimen.

Hybrid nanophotonic-nanomagnonic SiC-YiG quantum sensor: I/theoretical design and properties

Here I present the theory of a new hybrid paramagnetic-ferrimagnetic SiC-YiG quantum sensor. It is designed to allow sub-nanoscale single external spin sensitivity optically detected pulsed electron electron double resonance spectroscopy, using an X band pulsed EPR spectrometer and an optical fiber. The sensor contains one single V2 negatively charged silicon vacancy color center in 4H-SiC, whose photoluminescence is waveguided by a 4H-SiC nanophotonic structure towards an optical fiber. This V2 spin probe is created by ion implantation at a depth of few nanometers below the surface, determined by optically detected paramagnetic resonance under the strong magnetic field gradient of a YiG ferrimagnetic nanostripe located on the back-side of the nanophotonic structure. This gradient also allow the study, slice by slice at nanoscale, of the target paramagnetic sample. The fabrication process of this quantum sensor, its magnetic and optical properties, its external spins sensing properties in a structural biology context, and its integration to a standard commercially available pulsed EPR spectrometer are all presented here.

Magnetic Octupole Response of Dielectric Quadrumers

AbstractThe development of new approaches to tuning the resonant magnetic response of simple all‐dielectric nanostructures is very important in modern nanophotonics. Here, it is shown that a resonant magnetic octupole (MOCT) response can be obtained by dividing a solid rectangular silicon block to a quadrumer structure with the introduction of narrow gaps between four nanocubes. The spectral position of the MOCT resonance is controlled and tuned by varying the distance between the nanocubes. It is demonstrated that several magnetic hot‐spots related to the MOCT resonance can be located in the gaps creating a strong magnetic field gradient in free space. It is observed that the resonant excitation of the MOCT moment leads to a significant enhancement of light absorption in the system at the spectral region, where light absorption in bulk silicon is weak. The results of this work can be applied to design new composite antennas and metamaterials based on complex building blocks, energy harvesting devices, and molecular trapping with magnetic hot‐spots.