The rotational anisotropies in the ferromagnetism/antiferromagnetism 1/ antiferromagnetism 2 exchange bias structures

The rotational anisotropies in the exchange bias structures of ferromagnetism/antiferromagnetism 1/antiferromagnetism 2 are studied in this paper. Based on the model, in which the antiferromagnetism is treated with an Ising mean field theory and the rotational anisotropy is assumed to be related to the field created by the moment induced on the antiferromagnetic layer next to the ferromagnetic layer, we can explain why in experiments for ferromagnetism (FM)/antiferromagntism 1 (AFM1)/antiferromagnetism 2 (AFM2) systems the thickness-dependent rotational anisotropy value is non-monotonic, i.e. it reaches a minimum for this system at a specific thickness of the first antiferromagnetic layer and exhibits oscillatory behaviour. In addition, we find that the temperature-dependent rotational anisotropy value is in good agreement with the experimental result.     

一种含势阱具有混合交换势形式的平均原子模型

对传统的简单平均原子模型（AAM）作了改进：1使用了动态自由电子判据；2将自由电子分为三种类型，分别用分波法和统计方法加以处理；3应用变分原理给出了一种混合形式的交换势取代了Slater势；4应用材料常态常数标定了原子结构中的参数.作为算例，计算并与实验比较了Fe,Ni,Cu的零温电子压强. 关键词： 平均原子结构 交换势 电子压强     

氯化锌修饰蓝光量子点发光二极管EI北大核心CSCD

采用氯化锌(ZnCl_(2))修饰镉基CdSe/ZnS蓝光量子点(B-QD)薄膜,发现与量子点表面结合力更强的ZnCl_(2)能够部分取代量子点长链配体油酸,有效钝化量子点表面缺陷,提高薄膜的荧光量子效率(PLQY)。此外,由于ZnCl_(2)具有偶极作用,使量子点真空能级提高0.2 eV,一方面可改善电子和空穴载流子注入平衡,另一方面可有效降低发光器件的启亮电压,提高器件的发光寿命。这种无机配体修饰量子点薄膜的方法可能为解决蓝光量子点发光二极管(B-QLEDs)因空穴注入困难和量子点表面缺陷导致器件性能不高的问题提供一个有效思路。     

最近邻弱交换相互作用对纳米管中Blume-Capel模型热学性质的研究

利用有效场理论研究了纳米管上最近邻弱交换相互作用下spin-1纳米管中Blume-Capel模型的内能、比热和自由能,得到了系统的内能、比热和自由能与最近邻弱交换相互作用和晶场的关系。结果表明：最近邻弱交换相互作用和晶场强度等诸多因素相互竞争,使系统表现出比 = = =1时的BC模型更为复杂的热学性质;系统内能随温度的变化曲线表现出不连续性;比热随温度的变化出现奇异性;高温对自由能的影响更加明显。     

最近邻强交换相互作用对spin-1纳米管热力学性质的影响

利用有效场理论研究了纳米管上最近邻强交换相互作用下Blume-Capel模型的内能、比热和自由能,得到了系统的内能、比热和自由能与最近邻强交换相互作用、晶场强度和温度的关系.结果表明:最近邻强交换相互作用、晶场强度和温度等诸多因素相互竞争,使系统表现出比J_1=J_2=J=1时的BC模型更为丰富的热力学性质;系统内能随温度的变化曲线表现出不连续性;比热随温度的变化出现奇异性;一定条件下,基态时的自由能会发生突变.     

A lattice scenario for a proton radiography accelerator

A proton radiography system is an accelerator-based facility.Especially high-energy proton radiography is an advanced hydrodynamics diagnostic tool,and it is the trend of radiography technology development.In this paper,a 20 GeV accelerator complex scenario,including a 35 MeV linac,a 1 GeV booster and a 20 GeV main ring,is introduced.The overall physics design of the proton radiography accelerator is described,including the design of each part of the accelerator and the choice of the main parameters.     

低能质子在半导体材料Si 和GaAs中的非电离能损研究

非电离能损(NIEL)引起的位移损伤是导致空间辐射环境中新型光电器件失效的主要因素.由于低能时库仑相互作用占主导地位,一般采用Mott-Rutherford微分散射截面,但它没考虑核外电子库仑屏蔽的影响.为此,本文采用解析法和基于Monte-Carlo方法的SRIM程序计算了考虑库仑屏蔽效应后低能质子在半导体材料Si,GaAs中的NIEL,SRIM程序在计算过程中采用薄靶近似法, 并与其他作者的计算数据和实验数据进行了比较.结果表明：用SRIM程序计算NIEL时采用薄靶近似法处理是比较合理的,同时考虑库仑 关键词： 低能质子 非电离能损 硅 砷化镓     

晶场二级效应与交换作用对PrF3晶体磁性及磁光性质的影响

研究了晶场二级效应在PrF₃晶体中的作用，发现该效应可使Pr³⁺离子的晶场单态与其他态混合，对PrF₃晶体磁化率产生明显影响.进一步研究了晶体内的交换作用有效场，其形式为H_in=(1.9-0.02556T)×10^-5M，在100—300 K的温度范围内，以此计算的PrF₃晶体的倒数磁化率和Verdet常数的倒数与实验值符合较好.结果表明，在PrF₃晶体中，晶场二级效应与离子间的交换作用都不能忽略. 关键词： 晶场二级效应 交换作用有效场 Verdet常数 3晶体')" href="#">PrF₃晶体     

Theoretical study on the mechanism for the excited-state double proton transfer process of an asymmetric Schiff base ligand

Excited-state double proton transfer (ESDPT) in the 1-[(2-hydroxy-3-methoxy-benzylidene)-hydrazonomethyl]-naphthalen-2-ol (HYDRAVH₂) ligand was studied by the density functional theory and time-dependent density functional theory method. The analysis of frontier molecular orbitals, infrared spectra, and non-covalent interactions have cross-validated that the asymmetric structure has an influence on the proton transfer, which makes the proton transfer ability of the two hydrogen protons different. The potential energy surfaces in both S₀ and S₁ states were scanned with varying O-H bond lengths. The results of potential energy surface analysis adequately proved that the HYDRAVH₂ can undergo the ESDPT process in the S₁ state and the double proton transfer process is a stepwise proton transfer mechanism. Our work can pave the way towards the design and synthesis of new molecules.     

基于薄膜编码超表面的宽频超薄声散射体

该文提出了一种基于薄膜编码超表面的宽频超薄声散射体。利用附加质量块的薄膜和空气腔组成的薄膜结构构建了反射声波相位差接近180°的两种共振单元。将两种共振单元按照一定的顺序进行排列,可以组成深亚波长尺寸下的声学超表面。所构建的声学超表面可以产生宽频有效的散射声场。通过有限元仿真软件对多个频率的近场散射声场分布、远场声指向性和扩散系数进行了仿真计算,仿真结果显示,该散射体可以高效地散射入射声波,并且散射效果在一定的频率范围内是宽频有效的。