第三类磁点群的Molien函数

本文把Landau连续结构相变对称理论中的Molien函数计算公式推广到磁群共表示情形,导出了所有第三类(共58个)Shubnikov磁点群的Molien函数,这些函数可以直接应用于连续磁相变的对称理论。     

抗坏血酸同顺磁离子Mn~(2+)、Gd~(3+)络会的~(13)C NMR研究

该文用顺磁离子对其近邻~(13)C核的NMR吸收增宽效应,系统地研究了抗坏血酸在不同溶剂中对金属离子Mn~(2+)、Gd~(3+)的配合行为.在水溶液中,抗坏血酸可通过两种配合方式与Mn~(2+)作用,但与Gd~(3+)的作用只有一种稳定的结构.在水中抗坏血酸对金属的配位活性部位分别是1位羟基氧,3位离解的羟基氧和6位羟基氧.在DMSO中,3位羟基由于H~+对该基团的静电遮蔽而变得对金属离子Mn~(2+)表现为配位惰性,同时6位羟基配位活性较大增强.对Gd~(3+)来说,此时没有优势配位活性部位存在.文章还讨论了抗坏血酸在H_2O-DMSO混合溶剂中的~(13)C NMR谱及在DMSO中NaOH对其~(13)C NMR谱及其与金属络合结构的影响.     

Pseudo-Spin-Valve Trilayer Using Amorphous CoNbZr Layer： Giant Magnetoresistance, Domain Structures and Potentials for Spin-Electronic Devices

We propose a pseudo-spin-valve (PSV) trilayer using amorphous CoNbZr Mloy for soft magnetic layers. The giant magnetoresistance (GMR), domain structures and their variation upon thermal annealing are investigated. The GMR effect is not only stable up to 300℃ but also enhanced due to the improvement of the interfaces between Cu and magnetic layers. With high annealing temperature, the magnetoresistance (MR) ratio decreases rapidly as a result of serious layer interdiffusion. Dense stripe domains, which disappear after annealing at 300℃ for 1h, are observed in the sandwiched films. It is found that after patterning to elliptic stripe with aspect ratio of 6:1, the trilayers have a single domain and their MR ratio increases. The dynamic MR behaviour under an ac magnetic field indicates that the patterned stripes have good linear MR responses. Therefore, it is believed that the CoNbZr/Cu/Co PSV trilayers have strong potentials for spin-electronic devices including magnetic random access memory.     

Effect of Magnetic Field and Equilibrium Flow on Rayleigh-Taylor Instability

We investigate the effect of a finite equilibrium flow and magnetic field on the Rayleigh-Taylor instability. It is found that the equilibrium flow only makes a frequency shift of perturbation and the growth rate of the Rayleigh-Taylor instability remains unchanged. However, the magnetic field can change the growth rate and, in particular,a very strong magnetic field suppresses the growth rate.     

Supercontinuum Generation in a Photonic Crystal Fibre

Nearly 1000-nm broad continuum from 390 nm to 1370 nm is generated in a 2-m long photonic crystal fibre. The maximum total power of supercontinuum is measured to be 60mW with the pumping power of 800mW output from a 200-fs Ti:sapphire laser. The evolution of the pumping light into supercontinuum is experimentally studied in detail. It is found that the mechanism for supercontinuum generation has direct relations with Raman effect and soliton effect, and the four-wave mixing plays an important role in the last phase of the supercontinuum generation.     

超磁致伸缩材料国际会议情况介绍

日本高科技协会，于1996年11月6日-8日在美国夏威夷火努鲁鲁的日本东海大学太平洋中心组织召开了稀土超磁致伸缩材料基础和应用研究的国际会议．超磁致伸缩材料GMM（GiantManetostrictiveMa．tenals）为稀土元素钛Tb（Terbium）、镐Dy（DysPro－sium）和铁Fe的合金化合物，其基     

玻色—爱因斯坦凝聚和兰姆位移

扼要地介绍了ＢＥＣ研究的近况和研究方向，同时报道了我们在ＢＥＣ的光散射和兰姆位移方面的研究工作