Papers by Keyword: Magnetic Resonance

Abstract: 0.85La_0.7Sr_0.3MnO₃/0.15GeO₂ composite material and pure La_0.7Sr_0.3MnO₃ were investigated by X-ray diffraction, scanning electron microscopy, magnetometry and magnetic resonance methods. It was observed that both samples demonstrate the ferromagnetic properties, while the absolute value of the magnetization, the magnetic entropy change and the magnetic ordering temperature decrease in composite in comparison with pure La_0.7Sr_0.3MnO₃. The magnetic resonance spectra of investigated (1-x)La_0.7Sr_0.3MnO₃/xGeO₂ (x=0, 0.15) can be attributed to the superposition of magnetic resonance spectra from magnetically anisotropic particles with different orientations.

Abstract: Within the kinetic energy driven superconducting mechanism, we have studied the temperature dependence of commensurate magnetic resonance in cuprate superconductors. It is shown that the commensurate magnetic resonance peak at the antiferromagnetic wave vector point persists in the superconducting state until the temperature rises to the superconducting transition temperature $T_{\rm c}$. The intensity of the resonance peak decreases with increasing temperature which is just like the temperature dependence of the superconducting gap parameter. Our results are in qualitative agreement with the inelastic neutron scattering experimental data and reflect that the commensurate magnetic resonance is closely related to the creation of the charge carrier pairs and thus the superconducting mechanism of cuprate superconductors.

Abstract: In this work, we study the effects of NO anneals on the interface of 4H-SiC MOSFETs via spin dependent charge pumping, an electrically detected magnetic resonance technique. We make measurements at high and ultra-low resonance frequencies. Our results indicate that the NO anneals both change the silicon vacancy energy levels as well as induces disorder at the interface. In addition, our results indicate that the changes in energy levels involve N atoms very close to V_Si sites.

Abstract: Nanoclusters and nanocrystals of the room temperature magnetic spinel CuCr₂S₄ synthesized using a facile solution-based method were examined by magnetic resonance in a wide frequency range 9.6÷80 GHz and at temperatures down to 4.2 K. Decreasing of the resonance field and broadening of the resonance lines are found below ∼ 50 K for both the nanocluster and nanocube samples due to the freezing of magnetic moments of nanocubes and nanocrystalline particles constituting nanoclusters. Additional blocking temperature T_b≅300 K appears in nanoclusters due to the freezing of the magnetic moment of the entire cluster as a whole. Below this temperature, an additional low-field resonance line is found in the resonance spectra of nanoclusters at X-band.

Abstract: This work presents the results of studies of electromagnetic properties of nanocomposites based on opal matrices in the millimeter wavelength range. It is shown that the application of an external magnetic field changes the transmission and reflection coefficients. Magnetic resonance was studied in nanocomposite particles of spinel ferrites or metals. Magnetic resonance spectra were restored. We considered the parameters of nanocomposites required for using in microwave devices.

Abstract: this device designed a wireless power supply based on IAP15F2K61S2 single-chip microcomputer control device, the device using the theory of electromagnetic resonance to simulate future wireless charging way; Is application of a wireless power supply technology in an attempt to relieve the energy crisis. System to IAP15F2K61S2 microcontroller as the control core, high power wireless transmission is realized by using xkt409 electricity. Charging status can be displayed on the LCD screen, wireless charging model to simulate the future car.

Abstract: Magnetic resonance wireless power transmission technology is based on the phenomenon of resonant coupling to realize non-contact power transmission via near magnetic field. Based on the mutual coupling model of resonance system, the influence laws of system transmission parameters, such as coil coupling coefficients, load resistance, etc., on the transmission performance are theoretically studied in this paper. The research results shows that the power high-efficiency and high-quality transmission does not depend on the large coil loop coupling coefficient and the working frequencies of maximum power and maximum efficiency transmission do not coincide at most condition. Transmission systems with a high resonance frequency can produce high power and efficiency transmission over short distances. In addition, by increasing the coil diameter or wire diameter can improve the system quality factor, and optimize the energy transmission performance.

Abstract: Magnetic resonance wireless power transmission uses resonance strong coupling between the transmission and receiving terminals to realize a non-contact efficient supply of energy over large distance. The transmission power, efficiency and distance are confirmed by comprehensive function of the transmission parameters. By taking experimental means, the influence laws of loop transmission parameters, such as separation between coils, coil size, etc., on the transmission performance are studied in this paper. The experimental results show that the power high-efficiency and high-quality transmission does not depend on the large coil loop coupling coefficient and transmission power and efficiency may increase firstly and then decline as the separation between coils increases. The transmission performance can be optimized by increasing the coils diameter or wire diameter, and moreover, transmission systems with a high resonance frequency can produce high power and efficiency transmission over short distances.

Abstract: It uses MSP430F2274, the ultra low power microcontroller, as the control core of short circuit detection device, through the accurate measurement of low voltage circuit breaker load side of the main wiring of insulation resistance value and the interphase insulation resistance value, outputting high voltage startup sound and light alarm device, and then accomplish the open circuit fault detection. Testing power supply is the use of magnetic coupling resonance principle, from the main power grid electrical insulation for short circuit detection device. The device has the advantages of low cost, small volume, good safety, good detection effect, and can be embedded in use in low voltage circuit breaker.

Abstract: The analysis of magnetic coupling resonance based on Mode Coupling theory is often complicated and abstract. Moreover, this theory is inconvenient when it comes to designing the circuits. Based on the mutual inductance in the circuit, we completed theoretical derivation, parameters calculation and circuit simulation for each of the two-coil and the four-coil structure. The received power and the transmission efficiency under different conditions are analyzed and compared. Experimental results show that too high or too low resonant frequency will affect the efficiency of transmission and reception of energy in the two-coil structure, a problem of optimal distance for energy transmission is existed in four-coil structure, the resonant frequency of the system will also affect the distance.