自旋玻璃的实验和理论综述

材料的磁性可以许多形式(如铁磁性、顺磁性、反铁磁性、逆磁性等)存在.至今,还没有一个统一的理论能解释物质的各种磁性,也不能认为人们对磁性的各种形式都已了解清楚.人们对磁性的认识仍在不断发展之中. 1972年,V.Cannella和J.A.Mydosh[1]首先在Au1-xFex(x<15%)中观察到自旋玻     

A Practical Guide for X-Ray Diffraction Characterization of Ga（A1, In）N Alloys

Ca(In, Al)N alloys are used as an active layer or cladding layer in light emitting diodes and laser diodes, x-ray diffraction is extensively used to evaluate the crystalline quality, the chemical composition and the residual strain in Ca(Al,In)N thin films, which directly determine the emission wavelength and the device performance. Due to the minor mismatch in lattice parameters between Ca(Al, In)N alloy and a CaN virtual substrate, x-ray diffraction comes to a problem to separate the signal from Ca(Al,In)N alloy and CaN. We give a detailed comparison on different diffraction planes. In order to balance the intensity and peak separation between Ca(Al,In)N alloy and CaN, (0004) and (1015) planes make the best choice for symmetric scan and asymmetric scan, respectively.     

sine-Gordon模型中旋转对称孤子解的动力学及其在大面积Josephson结方面的应用

用集体坐标和拉格朗日变分原理为基础的微扰论处理了n+1维旋转对称的sine-Gordon孤子在远离原点处受微扰势作用下的行为。强调孤子的粒子性并从正则方法导出其依赖于位置的广义动量和运动方程。这一方法可以处理一类相当广泛的微扰势而无需其具体形式即可定性地讨论孤子的行为。在无耗散条件下,研究了孤子的速度-位置相空间的特性,分析了诸如回波效应、不稳定不动点和逃逸等各种可能的现象。引入耗散后,得到了修正的运动方程。还讨论了上述结果在大面积Josephson结方面的应用,并与数值计算的结果作了比较,两者符合较好。     

Translational Invariance in Phase Diagram of S = 1／2, 3／2 Spin Glass Systems

By using the replica method and the functional integral technique, the quantum XY spin glass model with ferromagnetic coupling is investigated numerically. From the numerical results of the thermodynamic and magnetic quantities we found that these quantities do not vary with the mean exchange interaction when the mean exchange interaction is lower than 1. This feature demonstrates that there are the mean interaction translational symmetries in the spin-glass and paramagnetic phases.     

SOME RESULTS ON A DEGENERATE AND SINGULAR DIFFUSION EQUATION

In this article,a degenerate and singular diffusion problem is studied.The ex- istence of solutions is established by parabolic regularization.Some properties of solutions, for instance,asymptotic behavior,are also discussed.     

Effects of Magnetic Coupling on Profile of Emission Lines and Images of an Accretion Disc Around a Black Hole

The profiles of emission lines and images of an accretion disc around a black hole (13tt) are simulated by considering the effects of the magnetic coupling (MC) of a central BH with the disc. The MC effects are discussed for both slow- and fast-spinning BHs, and the following results are obtained. Firstly, the width of the emission lines and the brightness of the disc are reduced and augmented for slow- and fast-spinning BHs, respectively. Secondly,the image of the disc becomes dimmer and brighter near the inner edge of the disc for slow- and fast-spinning BHs, respectively. It turns out that all these results arise from the MC effects on the position of the dominant emission region of the accretion disc.     

圆域超导隧道结Sine-Gordon方程的旋转周期解

圆域隧道结在恒流源驱动下,结两侧的超导体序参数的位相差随时间和空间的变化满足二维sine-Gordon方程。数值计算的结果表明,方程存在旋转周期解。在旋转周期解的条件下,沿径向各点结两侧的电势差对时间的平均值相等,瞬时电压和电流密度的超流部分随时间的变化沿径向的分布呈波动方式传播,而电流密度沿径向向结中心作衰减传播。     

弯曲壁面上双排离散孔的流量不等时气膜冷却特性的试验研究

本文是以数千个实验数据为基础,定量地给出了在前后排孔流量不等时,在整个凹面和凸面上的气膜冷却有效温比分布的全貌,使人们清楚地看出在不同条件下不同曲面上的特征。为设计者提供了有实际价值的依据。同时还对射流中的二次流的现象与规律进行了探索性的分析,值得进一步探索和研究。     

药物离子选择性电极响应规律的系统研究——Ⅲ.红霉素电极及其对季铵的选择性规律

本文研究了多种红霉素电极。电极对于季铵的选择性可用诱导效应和空间位阻效应来定量说明,符合方程式logK_(ij)=a_1I-a_2Z/R+a_0,式中I为诱导效应指数,a_1,a_2,a_0为与电活性物有关的系数。建立了阳离子型药物电极K_(ij)对季铵烷基链碳原子数n的关系的一般数学模型:logK_(ij)=A/2.7~n+B/(0.80+1.26n)+C。证明:随着碳原子数增大,logK_(ij)趋于一极限值C。此处A,B,C为与电活性物有关的系数。     

顺磁性对单晶GdBa_2Cu_3O_（6＋y）临界电流密度的影响

由于单晶ＤｄＢａ２Ｃｕ３Ｏ６＋ｙ样品中Ｇｄ３＋离子本身固有的磁矩对样品有顺磁贡献，使得样品的磁滞回线有所倾斜并使磁滞回线的宽度增大，因而使根据Ｂｅａｕ模型得到的临界电流密度偏离了其真正的值．在温度Ｔ＝４．２Ｋ时，偏离达到８％．因而在对ＹＭＯ和ＧＢＣＯ进行比较研究时，对ＧＢＣＯ临界电流密度的修正是必要的．这一顺磁磁化强度的磁场依赖关系可以用反铁磁的分子场理论给以很好的描述．