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Perpendicularly oriented barium ferrite thin films with low microwave loss,prepared by pulsed laser deposition 下载免费PDF全文
Barium ferrite(Ba M) thin films are deposited on platinum coated silicon wafers by pulsed laser deposition(PLD).The effects of deposition substrate temperature on the microstructure,magnetic and microwave properties of Ba M thin films are investigated in detail.It is found that microstructure,magnetic and microwave properties of Ba M thin film are very sensitive to deposition substrate temperature,and excellent Ba M thin film is obtained when deposition temperature is 910℃ and oxygen pressure is 300 m Torr(1 Torr = 1.3332×10~2Pa).X-ray diffraction patterns and atomic force microscopy images show that the best thin film has perpendicular orientation and hexagonal morphology,and the crystallographic alignment degree can be calculated to be 0.94.Hysteresis loops reveal that the squareness ratio(M_r/M_s) is as high as 0.93,the saturated magnetization is 4004 Gs(1 Gs = 10~4T),and the anisotropy field is 16.5 kOe(1 Oe = 79.5775 A·m~(-1)).Ferromagnetic resonance measurements reveal that the gyromagnetic ratio is 2.8 GHz/kOe,and the ferromagnetic resonance linewith is108 Oe at 50 GHz,which means that this thin film has low microwave loss.These properties make the Ba M thin films have potential applications in microwave devices. 相似文献
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Propagation properties of off-axis Hermite--cosh--Gaussian beam combinations through a first-order optical system 下载免费PDF全文
Based on the Collins integral formula, the analytic expressions of propagation of
the coherent and the incoherent off-axis Hermite--cosh--Gaussian (HChG) beam
combinations with rectangular symmetry passing through a paraxial first-order
optical system are derived, and corresponding numerical examples are given and
analysed. The resulting beam quality is discussed in terms of power in the bucket
(PIB). The study suggests that the resulting beam cannot keep the initial intensity
shape during the propagation and the beam quality for coherent mode is not always
better than that for incoherent mode. Reviewing the numerical simulations of
Gaussian, Hermite--Gaussian (HG) and cosh--Gaussian (ChG) beam combinations
indicates that the Hermite polynomial exerts a chief influence on the irradiance
profile of composite beam and far field power concentration. 相似文献
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Texture and self-biased property of an oriented M-type barium ferrite thick film by tape casting 下载免费PDF全文
In this paper,the oriented M-type barium ferrite(BaM) thick films with different thicknesses are prepared by tape casting.It is found that the crystallographic alignment degree(f),the pore and the squareness ratio(Mr/Ms) are not affected by the thickness of the film.XRD and SEM results show that the thick film has hexagonal morphology with a crystal texture of c-axis grains perpendicular to film plane.The hysteresis curve indicates that the BaM thick film exhibits a self-biased property with a remanent magnetization of 3.30 T,a squareness ratio(Mr/Ms) of 0.81,and a coercivity of 0.40 T.The results show that the BaM thick film has potential for use in self-biasing microwave devices,and also proves that the tape casting technique is capable of fabricating high-quality barium ferrite films,thus providing a unique opportunity to realize the large area production of thick film. 相似文献
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Undoped and V-doped 6H-SiC single crystals have been grown by the physical vapor transport method.The V concentration is determined to be 3.76×1017 at/cm3 and 6.14×1017 at/cm3 by secondary ion mass spectrometry for low V-doped and high V-doped SiC samples,respectively.The undoped 6H-SiC shows diamagnetism,while the V-doped 6H-SiC exhibits weak ferromagnetism.The lower V-doped sample shows stronger ferromagnetism compared to that of the higher V-doped sample.However,the structural characterization indicates that the lower V-doped SiC has a relative poor crystalline quality.It is found that both V dopants and defects are essential for introducing ferromagnetic exchange in V-doped SiC single crystals. 相似文献
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