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- electromagnetic pulse
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- Intelligent Medical Engineering
- Southern University of Science and Technology
- Politehnica University of Timi?oara
- Wroclaw University of Technology
- Centro de laseres pulsados
- Szchenyi Istvn University
- ELI-ALPS, ELI-HU Non-Profit Ltd.
- V.N. Karazin Kharkiv National University
- Politecnico di Torino
- Centro de laseres pulsados and University of Salamanca
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Giant exchange bias in the single-layered Ruddlesden-Popper perovskite
摘要： Exchange bias (EB) as large as ～5.5 kOe is observed in SrLaCo0.5Mn0.5O4, which is the highest ever found in any layered transition-metal oxides including Ruddlesden-Popper series. Neutron-diffraction measurement rules out long-range magnetic ordering and together with dc magnetic measurements suggests formation of short-range magnetic domains. Ac magnetic susceptibility, magnetic memory effect, and magnetic training effect con?rm the system to be a cluster spin glass. By carrying out density functional calculations on several model con?gurations, we propose that EB is originated at the boundary between Mn-rich antiferromagnetic and Co-rich ferromagnetic domains at the subnanoscale. Reversal of magnetization axis on the Co side alters the magnetic coupling between the interfacial Mn and Co spins, which leads to EB. Our analysis infers that the presence of competing magnetic interactions is suf?cient to induce exchange bias and thereby a wide range of materials exhibiting giant EB can be engineered for designing novel magnetic memory devices.
关键词： Ruddlesden-Popper perovskite,Exchange bias,cluster spin glass,magnetic memory devices
更新于2025-09-23 15:21:21
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Incorporating Surface Convection into a 3D Babcock–Leighton Solar Dynamo Model
摘要： The convective ?ows observed on the photosphere (e.g., supergranulation, granulation) play a key role in the Babcock–Leighton (BL) process to generate large-scale polar ?elds from sunspot ?elds. In most surface ?ux transport (SFT) and BL dynamo models, the dispersal and migration of surface ?elds are modeled as an effective turbulent diffusion. Recent SFT models have incorporated explicit, realistic convective ?ows in order to improve the ?delity of convective transport but, to our knowledge, this has not yet been implemented in previous BL models. We present the ?rst kinematic 3D Flux-Transport/BL model to explicitly incorporate realistic convective ?ows based on solar observations. Though we describe a means to generalize these ?ows to 3D, we ?nd that the kinematic small-scale dynamo action they produce disrupts the operation of the cyclic dynamo. The cyclic solution is found by limiting the convective ?ow to act only on the vertical radial component of the magnetic ?eld. The results obtained are generally in good agreement with the observed surface ?ux evolution and with non-convective models that have a turbulent diffusivity of the order of 3×1012 cm2 s?1 (300 km2 s?1). However, we ?nd that the use of a turbulent diffusivity underestimates the dynamo ef?ciency, producing weaker mean ?elds and a shorter cycle than in the convective models. Also, the convective models exhibit bands of mixed polarity in the polar regions that have no counterpart in solar observations, and the poleward migration speed of poloidal ?ux is determined mainly by the meridional ?ow and the vertical diffusion.
关键词： Sun: photosphere,Sun: magnetic ?elds,Sun: interior
更新于2025-09-23 15:21:21
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Low-profile wideband Fabry-Perot resonator antenna using artificial magnetic conductor surface
摘要： A low-profile, high gain Fabry-Perot Resonator antenna with a wide operation bandwidth (BW) is presented in this paper. The proposed design consists of an ellipse-shaped dipole as a wideband radiating source, which is reflected by an artificial magnetic conductor ground plane to achieve low-profile structure. The antenna gain can be significantly enhanced by the use of a half-wavelength-thick dielectric slab as a partial reflecting surface. Additionally, this dielectric slab also contributes to improving the radiation pattern characteristics of the proposed design, especially in the high frequency region. A final prototype with an overall size of 1.2λL × 1.2λL × 0.4λL (λL is free-space wavelength at the lowest frequency of 3-dB gain BW) has been fabricated to validate the concept. The measured results show that the proposed antenna yielded a wide 3-dB gain BW of approximately 50.3% with a peak gain of 14 dBi and impedance matching BW of 48.9%.
关键词： high gain,wideband,artificial magnetic conductor,half-wavelength dielectric slab,Fabry-Perot antenna,low profile
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - A Magnetic Focused CNT Travelling Wave Tube
摘要： A magnetic focused X-band travelling wave tube based on carbon nanotube cathode is presented. The travelling wave tube is operated in a uniform axial magnetic field. The extra magnetic field alleviates the electron beam focusing difficulty of electron gun and so allows it has a rather simple structure. The fabricated travelling wave tube is tested in a superconducting system and an electron beam transmittance of 86% is obtained.
关键词： Magnetic focused,Carbon nanotubes,Field emission cathodes,Travelling wave tubes
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Spin resolved Imaging with Scanning Field-Emission Microscopy
摘要： Secondary electrons emitted from a scanning field-emission microscope are spin analyzed with a Mott detector. Spin polarization up to 15% is observed with a lateral resolution of less than 5 nm, with a potential resolution of even less than 1 nm. In this paper the proof of principle is conducted by comparing this method with a well-established method of spin mapping and with reference samples examined by these two microscopes.
关键词： Secondary Electrons,Magnetic Imaging,Electron Microscopy,Field Emission
更新于2025-09-23 15:21:21
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Functionalized Holmium-Doped Hollow Silica Nanospheres for Combined Sonodynamic and Hypoxia-Activated Therapy
摘要： The oxygen concentration dependence of sonodynamic therapy (SDT) and bioreductive therapy can be utilized to design the strategy of synergistic therapy. Herein, holmium-doped hollow silica nanospheres are synthesized and then sequentially modified with chlorin e6, carboxyl poly(ethylene glycol) silane, and prostate stem cell antigen (PSCA) monoclonal antibody. The resultant nanocomposite designated as HHSN-C/P-mAb has good biocompatibility and can specifically target cancer cells overexpressing PSCA. Due to the inner cavity structure and Ho doping, HHSN-C/P-mAb shows high ultrasound (US) imaging contrast capability and excellent high-field magnetic resonance contrast performance. HHSN-C/P-mAb can act as a nanocarrier for loading the bioreductive prodrug tirapazamine (TPZ), and the degradation of the hollow nanospheres under the trigger of acidic microenvironment favors the pH responsive release of TPZ from the material. Upon US irradiation, HHSN-C/P-mAb produces reactive oxygen species to kill the cancer cells, and importantly, the oxygen consumption during SDT induces an intratumoral hypoxic environment to activate the therapeutic function of codelivered TPZ, resulting in a high-effective synergistic therapy. The findings of this study highlight that HHSN-C/P-mAb is a versatile theranostic nanoplatform for efficient cancer treatment.
关键词： magnetic resonance imaging,sonodynamic therapy,ultrasound imaging,holmium-doped hollow silica nanosphere,bioreductive therapy
更新于2025-09-23 15:21:21
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Magnetic and optical behaviors of SnO2-x thin films with oxygen vacancies prepared by atomic layer deposition
摘要： SnO2-x thin films with different concentration oxygen vacancies were prepared by Atomic Layer Deposition (ALD). Specifically, the oxygen vacancy concentration was controlled by the oxidation pulse time during the ALD process. The crystal structure of the as-prepared thin films was determined by XRD, and the magnetic properties were measured by VSM, while the optical properties were measured by optical transmittance spectrum. The results showed that the oxygen vacancy concentration of the SnO2-x could be controlled by the oxidation pulse time, and the crystal structures, magnetic properties, and optical properties were largely impacted by the concentration of oxygen vacancy.
关键词： microstructure,thin film,magnetic,diffraction,nanocrystal,oxygen vacancy
更新于2025-09-23 15:21:21
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Synthesis of hollow spheres of BiFeO3 from nitrate solutions with tartaric acid: Morphology and magnetic properties
摘要： Single-phase powders of bismuth ferrite have been synthesized for the first time by ultrasonic spray pyrolysis from nitrate solution in the presence of tartaric acid. The produced powders consist of hollow spherical agglomerates with a mean diameter of ~1 μm. The influence of tartaric acid concentration on the synthesis temperature and morphology of hollow spheres was established. The agglomerate shells have open and closed pores. The mean values of the shell thickness and the ratios of closed and open pores were estimated and their dependence on the concentration of tartaric acid was found. It was shown that the magnetic properties are determined not only by the size of nanoparticles composing the agglomerates, but also by the morphology of hollow sphere shells.
关键词： hollow spheres,morphology,magnetic properties,multiferroics,bismuth ferrite
更新于2025-09-23 15:21:21
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Approximate photonic bandgaps of dielectric-magnetic one-dimensional photonic crystals
摘要： The one dimensional photonic crystals (1DPCs) that have both the permittivity and permeability varying periodically along the same direction are analyzed theoretically using the coupled-mode theory. The approximate band edge frequencies, center frequencies, and the bandgaps are derived for the axial propagation. The results are elegant generalization of the corresponding results of the dielectric 1DPCs. The approximate bandedge frequencies obtained were found to have good agreement with those obtained by the transfer matrix method.
关键词： One-dimensional photonic crystal,Coupled-mode theory,Dielectric-magnetic photonic crystal
更新于2025-09-23 15:21:21
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Binding energy and optical absorption of donor impurity states in “12-6” tuned GaAs/GaAlAs double quantum well under the external fields
摘要： We have investigated the binding energies of the s-symmetric ground and first excited shallow donor impurity states and the total 1s → 2s absorption coefficient, including the first and third order corrections, in "12-6" tuned GaAs/GaAlAs double quantum well as a function of the impurity position, size of the structure, and the electric and magnetic field intensities. The obtained results show that the electronic and optical properties of tuned GaAs/GaAlAs double quantum well can be adjustable by an appropriate choice of the sample geometry, material parameters and applied external fields which will lead to new potential applications in optoelectronics.
关键词： Double quantum well,Absorption coefficient,Electric and magnetic field,Donor impurity
更新于2025-09-23 15:21:21