强磁场中的逆Compton散射和Crab Pulsar的光学辐射

本文在非相对论极限下(B/B_q≤1,(?)_ω/mc^≤1),给出了强磁场中逆Compton散射的截面、偏振特性和散射光子能量的一般表达式,并在此基础上讨论了脉冲星外gap附近的次级高能粒子与gap脉动的低频光子的逆Compton散射产生Crab Pulsar光学辐射的可能性,这种机制可以较好地解释Crab Pulsar光学观测的主要特征。     

AD9221在软件无线电平台中的应用

本文根据软件无线电的特点,按照某专网通信的特殊要求,介绍了AD9221在软件无线电通用硬件平台中的应用,并给出该设计方案的硬件电路图和相关源代码     

手机干扰设备介绍与分析

随着移动通信业务的发展,手机己成为人们现代生活中必不可少的工具之一,但是问题也伴随而来.……     

High-Pressure Single-Crystal Neutron Scattering Study of Magnetic and Fe Vacancy Orders in （T1,Rb）：Fe4Se5 Superconductor

The recently discovered metal-intercalated iron selenide superconductors A2Fe4Se5 （A=K, Cs, T1- K, Rb, T1-Rb） （245） compounds, with Tc ～30K, have attracted much interest A high transition- temperature （TN ≈ 470-560K） and large magnetic moment （3.3μB/Fe） block antiferromagnetic （AFM） order exists in the superconducting samples. Mag- netic order-parameter experiences an anomaly when Tc is approached. The superconductors crystal- lize with a highly ordered √5 × √5 superstructure, in which the Fel site of the I4/m structure is only a few percents occupied and the Fe2 site is fully occupied. The non-superconducting samples at low-T also crystallize in the I4/m structure, while both Fe sites are fractionally occupied, since the numbers of the Fe vacancies in the samples and the vacant sites in the √5 × √5 pattern are mismatched. The partially ordered √5× √5 vacancy order becomes one of three competing phases for temperature below room temperature up to ～ 500K, namely, these sam- ples are phase-separated and in the miscibility gap 1lacier the n,mhi~nt condition.     

手机干扰设备介绍与分析

随着移动通信业务的发展,手机己成为人们现代生活中必不可少的工具之一,但是问题也伴随而来.     

Physics picture from neutron scattering study on Fe-based superconductors

Neutron scattering, with its ability to measure the crystal structure, the magnetic order, and the structural and magnetic excitations, plays an active role in investigating various families of Fe-based high-T c superconductors. Three different types of antiferromagnetic orders have been discovered in the Fe plane, but two of them cannot be explained by the spin-density-wave (SDW) mechanism of nesting Fermi surfaces. Noticing the close relation between antiferromagnetic order and lattice distortion in orbital ordering from previous studies on manganites and other oxides, we have advocated orbital ordering as the underlying common mechanism for the structural and antiferromagnetic transitions in the 1111, 122, and 11 parent compounds. We observe the coexistence of antiferromagnetic order and superconductivity in the (Ba,K)Fe 2 As 2 system, when its phase separation is generally accepted. Optimal T c is proposed to be controlled by the local FeAs 4 tetrahedron from our investigation on the 1111 materials. The Bloch phase coherence of the Fermi liquid is found crucial to the occurrence of bulk superconductivity in iron chalcogenides of both the 11 and the 245 families. Iron chalcogenides carry a larger staggered magnetic moment ( 2 μ B /Fe) than that in iron pnictides ( 1 μ B /Fe) in the antiferromagnetic order. Normal state magnetic excitations in the 11 superconductor are of the itinerant nature while in the 245 superconductor the spin-waves of localized moments. The observation of superconducting resonance peak provides a crucial piece of information in current deliberation of the pairing symmetry in Fe-based superconductors.     

封面故事

打破超导体里的库珀对的磁激发在超导能隙附近生成一对博戈留波夫准粒子.当库珀对的对称性要求轨道波函数在费米面上改变符号时,对应于库珀对里电子的相对动量处的磁激发强度趋于发散,形成非常规超导体磁激发谱的所谓自旋共振峰．磁激发谱可由非弹性中子散射实验直接观测．     

手机干扰设备介绍与分析

随着移动通信业务的发展,手机已成为人们现代生活中必不可少的工具之一,但是问题也伴随而来。比如在电影院、音乐厅里手机成为分散人们注意力的干扰源。又如在军队、公安、金融等需要保密的场合和单位,也很难避免手机的使用,有些手机甚至会在关机状态下自动开机,成为潜在窃听     

铁基高温超导体的中子散射研究

文章回顾了作者和合作者三年来应用中子散射技术方法,在铁基高温超导体研究中,通过测定材料的组分、晶体结构、反铁磁序结构、相变以及结构类型激发与磁性激发谱,对这些材料的微观物理过程与机理所做的初步理解和分析.