排序方式: 共有32条查询结果,搜索用时 265 毫秒
1.
2.
3.
应力长周期光纤光栅透射谱中旁瓣的抑制 总被引:1,自引:1,他引:0
提出一种优化应力长周期光纤光栅的实验方法.利用自行研制的机械结构,通过点接触施力写制应力长周期光纤光栅,并通过压力板V-M型形变实现优化MLPFG传输谱的n维调节,有效抑制了应力长周期光纤光栅传输谱中的旁瓣.当损耗峰LP05损耗强度为9.0 dB时,边模抑制比大于8.6 dB;同时,提出并实现了一种通过空气薄层形成的等厚干涉条纹来监测光纤上力分布的光学方法,从而为传输谱的优化提供有效参量. 相似文献
5.
6.
Role of defects in magnetic properties of Fe-doped SnO2 films fabricated by the Sol--Gel method 下载免费PDF全文
This paper obtains the room temperature ferromagnetism in Sn1 xFexO2 films fabricated by the Sol-Gel method.X-ray diffraction results show that Fe doping inhibits the growth of SnO2 and Fe3+ ions occupy the Sn sites.The measurement of resistance excludes the free carrier inducing ferromagnetism.Moreover,the temperature dependence of magnetization has been better fitted by the Curie-Weiss law and bound magnetic polaron(BMP) theory.An enhancement of ferromagnetism is achieved by annealing the samples with x = 7.1% in H2,and a decrease of oxygen flow rate.All these results prove that the BMP model depending on defects can explain ferromagnetism in diluted magnetic oxides. 相似文献
7.
Fabrication and Magnetic Properties of Co-Doped TiO2 Powders Studied by Nuclear Magnetic Resonance 下载免费PDF全文
Co0.04 Ti0.96O2 powders are fabricated by sol-gel method. The structure and magnetic properties are investigated under different annealing conditions systematically with emphasis on the influence of oxygen pressure. Pure anatase structure was acquired for all the samples annealed at 450℃ for one hour. The samples annealed in air exhibit evident room-temperature ferromagnetism (RTFM) with a small magnetic moment of 0.029μB per Co atom and coercivity Hc of 26 Oe, while the samples annealed in vacuum have strong RTFM with a larger magnetic moment of 1.18μB per Co atom and Hc of 430 Oe. The zero-field spin echo nuclear magnetic resonance spectrum of ^59Co is obtained to prove the existence of Co dusters in the latter samples, implying that the Co dusters are responsible for the strong RTFM in the samples annealed in vacuum. No Co cluster could be observed using both XPS and NMR techniques in the samples annealed in air, implying that the RTFM found in these sample sis intrinsic. 相似文献
8.
用射频磁控溅射方法制备了系列Co SiO_2 不连续磁性金属绝缘体多层膜 (DMIM) .经研究发现 :对 [SiO_2 (2 4nm) Co(t) ]2 0 体系 ,在Co层厚度小于 2 5nm时 ,Co层由连续变为不连续 ;Co层不连续时 ,其导电机理为热激发的电子隧穿导电 ,lnR与T- 1 2 接近正比关系 ;隧道磁电阻 (TMR)在Co层厚度为 1 4nm时出现极大值 - 3% .DMIM的性质不仅与磁性金属层厚度密切相关 ,而且与绝缘层厚度有密切的关系 .在固定Co层厚度为 1 9nm的情况下 ,研究了TMR随SiO_2 层厚度的变化关系 ,并给出定性的解释 .对 [SiO_2 (2 4nm) Co(2 0nm) ]2 0 的样品研究了TMR随温度的变化关系 ,发现TMR随温度的变化有一极大值 ,结合Helman的理论 (Phys.Rev .Lett,37,14 2 9(1976 ) ) ,认为是颗粒之间存在磁性耦合的结果 相似文献
9.
用射频磁控溅射方法制备了系列Co/SiO2不连续磁性金属绝缘体多层膜(DMIM) .经研究发现:对[SiO2(2.4 nm)/Co(t)]20体系,在Co层厚度小于2.5 nm时,Co层由连续变为不连续;Co层不连续时,其导电机理为热激发的电子隧穿导电,lnR与T-1/2接近正比关系; 隧道磁电阻(TMR)在Co层厚度为1.4 nm时出现极大值-3%.DMIM 的性质 不仅与磁性金属层厚度密切相关,而且与绝缘层厚度有密切的关系.在固定Co层厚度为 1.9 nm的情况下,研究了TMR随SiO2层厚度的变化
关键词:
不连续磁性金属/绝缘体多层膜
隧道磁电阻效应 相似文献
10.
钟文定所编《铁磁学》中册的出版,给大专院校的《铁磁学》课程及有关的科技人员提供了一本可贵的参考书.此书将有力地推动我国磁学和磁性材料学科的发展. 铁磁学是研究强磁性物质磁性起源、磁化机制、磁化过程及其对外界条件(如温度、压力等)的依从性规律的学科.由于磁性现象的复杂性,要将磁性材料的研究结果系统化并上升为规律性的认识是件比较困难的工作.各国学者为此进行了长期的努力.E.Kneller的“Fe-rromagnetismus”(1962),S.Chikazumi 的 “ Physics of Magnetism”(1964),A.H.Mo-rrish的“The Physical Principles of Magne-… 相似文献