Martensitic transformation and related magnetic effects in Ni-Mn-based ferromagnetic shape memory alloys

Ferromagnetic shape memory alloys, which undergo the martensitic transformation, are famous multifunctional materials. They exhibit many interesting magnetic properties around the martensitic transformation temperature due to the strong coupling between magnetism and structure. Tuning magnetic phase transition and optimizing the magnetic effects in these alloys are of great importance. In this paper, the regulation of martensitic transformation and the investigation of some related magnetic effects in Ni-Mn-based alloys are reviewed based on our recent research results.     

低温超导物理学中的重要实验史话

综观超导发展史，实验既是创立超导理论的基础，也是检验超导理论的惟一手段。正是实验的发展，不断揭示了超导的各种新现象，日益加深着人们对超导电性的认识，促进了超导物理学的发展和应用。文章回顾了低温超导发展过程中的一些重要实验，探讨了这些实验的思想及其对超导发展的重要促进作用。通过对超导实验历史材料的研究，我们不仅可以学到科研技能和了解科学新现象的发现过程，而且可以学到正确的科研态度和方法。     

类氢离子电离能的计算

在类氢离子电子束缚能一级相对论及电子自旋-轨道作用修正的基础上,考虑到原子核的质量效应及体积效应,计算了类氢离子的电离能,计算结果与文献提供的实验数据相符合,弥补了其他方法的不足.     

Magnetoimpedance of cobalt-coated silicon steels

Magnetoimpedance (MI) effect of cobalt-coated silicon steels is measured as a function of cobalt thickness (0−45 μm), DC magnetic field (0-2 kOe), frequency (1 kHz-1 MHz) and magnitude (1-20 mA) of AC current. With increase in deposition thickness, the MI ratio and the characteristic frequency are decreased because the samples are magnetically hardened by the coating. Nevertheless, cobalt deposition broadens the frequency-dependent MI curves, and the frequency range with a large MI ratio is extended. The variations of this peak width as well as the characteristic frequency and the MI ratio are explained by the skin effect and crossing effect.     

量子霍尔效应

从经典的霍尔效应开始,比较系统地、深入浅出地介绍了量子霍尔效应及其所涉及的一些新概念和实际应用。     

Ballistic transport in extended Datta-Das spin field effect transistors

The model of the Datta-Das spin field effect transistor [S. Datta, B. Das, Appl. Phys. Lett. 56 (1990) 665] is extended in several respects: (1) the Rashba effect and Dresselhaus effect coexist; (2) the incoming and outgoing leads are both ferromagnetic; (3) the interfacial scattering and band mismatch are taken into account. By using the Griffith boundary conditions, the transmission coefficients and, thus, the Landauer-Büttiker conductance are obtained analytically. The transmission probability and conductance of the spin field effect transistor are studied in detail.     

非相干耦合屏蔽光伏孤子对

预言了在有外加电场的光伏光折变晶体中存在着稳态非相干耦合的屏蔽光伏空间孤子对.这种孤子对是由偏振态和波长都相同的两束互不相干光耦合而成的.它可被看成是非相干屏蔽孤子对和非相干光伏孤子对的统一形式,当外加电场很强可忽略光伏效应时,它类似于已报 道的屏蔽孤子对,而当外加电场为零时,它相当于闭路条件下的光伏孤子对. 关键词： 光折变效应 空间光孤子 光伏效应     

约瑟夫森效应的一种初等阐述

用初等方法导出了约瑟夫森公式，阐述了约瑟夫森效应及其简单应用．     

光折变晶体BaTiO3中二波混频的温度效应

研究了光折变晶体钛酸钡中相向传输的二波混频的温度效应,得到在 BaTiO₃中增益耦合系数随温升而增加、并在85℃左右反向.说明其主要载流子的类型在此温度时发生改变.给出了有效陷阱浓度N(T)的温升模型,其理论预期值与实验数据符合较好.     

INCOHERENTLY COUPLED SCREENING-PHOTOVOLTAIC SOLITON FAMILIES IN BIASED PHOTOVOLTAIC PHOTOREFRACTIVE CRYSTALS

It is shown that the existence of incoherently coupled screening-photovoltaic soliton families is possible in biased photovoltaic photorefractive crystals under steady-state conditions. These screening-photovoltaic soliton families can be established provided the multiple incident beams have the same polarization and wavelength, and are mutually incoherent. Such soliton families reduce to screening-photovoltaic soliton pairs when they contain only two components. Relevant examples are presented where the photovoltaic photorefractive crystal is of the lithium niobate type.     

异常霍尔效应和自旋霍尔效应

异常霍尔效应和自旋霍尔效应是在常规霍尔效应的基础上引发出的2种新现象.本文介绍了这2种现象及其原理和潜在的应用.     

Geometric Treatment of the Gravitomagnetic Clock Effect

We have developed a general geometric treatment of the GCE valid for any stationary axisymmetric metric. The method is based on the remark that the world lines of objects rotating along spacely circular trajectories are in any case, for those kind of metrics, helices drawn on the flat bidimensional surface of a cylinder. Applying the obtained formulas to the special cases of the Kerr and weak field metric for a spinning body, known results for time delays and synchrony defects are recovered.     

应变液晶的负压光效应和反式压光效应

介绍聚合物分散液晶和应变液晶概念,给出聚合物分散液晶调光玻璃的"正压光效应"、"负压光效应"和"反式压光效应"三种效应定义.实验制备出负压光效应和反式压光效应新型应变调光玻璃样品,测试样品散射态雾度90%以上,半透明态透光率接近30%.用偏光显微术研究压光效应原理,表明对样品施加垂面按压或拉伸的应力诱导作用会引起液晶微滴中液晶分子具有某些特殊排列方式,导致样品光学性质发生显著变化.建立垂面拉伸液晶微滴模型,计算模拟所绘出的图形与偏光显微镜照片独特花样十分相似,进而合理解释了实验现象.应变液晶压光效应研究具有聚合物分散液晶基础研究意义和开发非电控调光玻璃的实际应用价值.     

From microelectronics to spintronics and magnonics

In this review, the recent developments in microelectronics, spintronics, and magnonics have been summarized and compared. Firstly, the history of the spintronics has been briefly reviewed. Moreover, the recent development of magnonics such as magnon-mediated current drag effect (MCDE), magnon valve effect (MVE), magnon junction effect (MJE), magnon blocking effect (MBE), magnon-mediated nonlocal spin Hall magnetoresistance (MNSMR), magnon-transfer torque (MTT) effect, and magnon resonant tunneling (MRT) effect, magnon skin effect (MSE), etc., existing in magnon junctions or magnon heterojunctions, have been summarized and their potential applications in memory and logic devices, etc., are prospected, from which we can see a promising future for spintronics and magnonics beyond micro-electronics.     

带宽对平顶高斯宽带激光传输特性的影响

研究了横向分布为平顶高斯模式的宽带激光在自由空间的传输特性,分析了频带宽度对其强度分布的影响。首先推导了平顶高斯模式宽带激光的每一频率分量在自由空间的传输公式,然后将频率域的传输公式通过傅里叶变换得到时间域的传输公式。基于推导的公式通过数值算例给出了不同频带宽度激光光束的强度分布结果,详细分析了空间模式的变化和时空耦合现象。研究结果表明:随着传输距离增大,平顶高斯空间模式趋于高斯分布。同时随着带宽增大,平顶高斯模式宽带激光表现出更强的时空耦合现象,并导致其空间横向分布发生明显变化。变化的主要特征为波前的强度分布随带宽增大而变窄,波后的强度分布则随带宽增大而远离轴中心向外扩展。     

叠加压缩相干态的量子统计性质

研究了叠加压缩相干态的量子统计性质,给出了压缩和反聚束效应与叠加系数之间的关系。结果表明,叠加压缩相干态具有压缩和反聚束的现象。压缩奇偶相干态的有关结果均作为特例包含在本文的一般结论之中。     

Saturation Effects in Mode-competition Effects of a Two-mode Laser with Multiplicative Noise

The full saturation effects in mode-competition effect of a two-mode laser with multiplicative noise are studied. By comparing a gain-noise model with a loss-noise model, it is found that the saturation term really has a great effect on mode-competition effects.     

光折变效应中二波耦合温度特性的研究

本文研究了光折变效应中,温度对晶体内空间电荷分布影响的微观机制,提出了空间电荷场的修正项,给出了钛酸钡晶体的空间电荷场与温度的理论曲线以及二波耦合中光强耦合系数与温度的理论曲线.     

薛定谔猫态的激发态

本文引入一类新的量子态,光子数添加藤定谔猫态,它由光场产生算符反复作用在薛定谔猫态上得到,并研究了在此态上表现出的压缩效应和反聚束效应.结果表明,添加光子数有助于光场出现反聚束效应,却使压缩效应受到抑制.