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Preparation And Research Of FeCoSi/MnIr FM/AFM Nano-multilayers

Posted on:2009-01-15Degree:MasterType:Thesis
Country:ChinaCandidate:J LiuFull Text:PDF
GTID:2120360245480966Subject:Condensed matter physics
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With the integration and miniaturization of electro-magnetic devices,the soft magnetic films with high saturation magnetization 4πMs,high electrical resistivityρ,low coercive force Hc(therefore,high permeabilityμ),have attracted more and more attention.At present, FM/AFM multilayers have large effective anisotropy field due to exchange bias field between ferromagnetic layers and antiferromagnetic layers.So,the multilayer system can obtain large in-plane anisotropy filed Hk and high ferromagnetic resonance frequency fr,simultaneously. Consequently,this kind of multilayer films have been one of the current hot topics.In this study,a series of FeCoSi/MnIr/FeCoSi multilayer films were deposited by RF magnetron sputtering.The structure was characterized by x-ray diffraction with Cu-Kαradiation.Magnetic properties were measured by a vibrating sample magnetometer(VSM). The permeability spectra of the samples were obtained by a shorted microstrip transmission-line perturbation method.The main contents are briefly introduced as follows:1)A series of FeCoSi / MnIr/FeCoSi multilayer films with Cu seed layer were fabricated successfully by improving experiment conditions and equipments.The XRD spectra for all samples shows that FeCoSi particles are bcc structure with(110)evident preferential orientation.2)It is seen that the influence of seedlayers for the soft magnetic properties of multilayer films is significant.In terms of experiments,Cu seedlayer is a better candidate for this multilayer system.The films with Cu seedlayers can reduce the He from 140Oe to 24Oe, and can obtain large effective anisotropy field Hk=74Oe.3)It is seen that the hysteresis loops of FeCoSi(t)/MnIr/FeCoSi(t)samples have two different exchange-bias field which is caused by the exchange coupling from two kinds of FM/AFM interface.For the sample with the FeCoSi layer thicknesst of 6nm,it shows good in-plane anisotropy and the exchange field Hex-top=206Oe,Hex-bottom=135Oe.On the other hand,exchange field Hex linearly decreases with 1/t(FeCoSi)4)The results of the permeability spectra of a series of FeCoSi/MnIr/FeCoSi multilayer films are followed:for the sample with t(FeCoSi)=50nm,the ferromagnetic resonance frequency fr is as high as 4.7 GHz,μ′is keep 167 and the imaginary componentμ″is less than 18 almost to 2 GHz;for the sample with t(FeCoSi)=12.5 nm,the ferromagnetic resonance frequency fr is more than 6.5 GHz.But the film with single FeCoSi layer has resonance frequency fr is 3.4 GHz.These results imply that the increase of exchange field between FM and AFM is benefit to improve the ferromagnetic resonance frequency fr.
Keywords/Search Tags:Nano-multilayers
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