Heisenberg and ferromagnetism

Heisenberg’s contributions to the understanding of ferromagnetism are reviewed. The special features of ferromagnetism, vis-a-vis dia and para magnetism, are introduced and the necessity of a Weiss molecular field is explained. It is shown how Heisenberg identified the quantum mechanical exchange interaction, which first appeared in the context of chemical bonding, to be the essential agency, contributing to the co-operative ordering process in ferromagnetism.     

CoNi/CoO 双层膜磁化反转机制与温度的依赖关系

Exchange coupling and magnetization reversal mechanism in two series of Co_xNi_(1-x)/CoO(30 nm)(x=0.2 and 0.4)bilayers are studied by vector magnetometer.Two components of magnetization are measured parallel and perpendicular to the applied field.At low temperatures,coercivity H_c∝(t_(FM))~(-n),n=1.5 and 1.38 for x=0.2 and 0.4,respectively,in agreement with the random field model.At room temperature,the coercivity is nearly proportional to the inverse FM layer thickness.In addition to the exchange field and the coercivity,the characteristic of the magnetization reversal mechanism was found to change with temperature.At temperatures below 180 K,magnetization reversal process along the unidirectional axis is accompanied only by nucleation and pinning of domain wall while magnetization rotation is also involved at high temperatures.     

铁棒磁化方式的研究

铁棒在磁铁上敲击磁化的效果优于将磁铁在铁棒上摩擦磁化的效果。     

贝特格子上纵场作用下的混合自旋模型性质研究

利用迭代方法,在铁磁情况下,研究了外场作用下二重Cayley树上自旋为1／2和3,2的混合Ising系统的热力学性质。通过数值求解,得出了亚晶格磁化强度MA,MB和总磁化强度M随温度变化的曲线。研究发现,亚晶格磁化强度MA、MB以及总的磁化强度在相同的外场条件下的变化趋势是一致的,只是饱和磁化强度数值有所不同,通过外场取值的不同,发现存在外场时与外场取零时磁化强度随温度变化趋势有所区别。结果还发现,铁磁情况下不管是否存在外场该系统都不存在三临界行为。     

机械合金法合成Fe25Ni75超细粉末的磁各向异性常数的研究

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　ＵｌｔｒａｆｉｎｅｐａｒｔｉｃｌｅｓｏｆｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓｓｕｃｈａｓＦｅ,Ｃｏ,Ｎｉａｎｄｔｈｅｉｒａｌｌｏｙｓｈａｖｅｔｈｅｐｏｔｅｎｔｉａｌａｐｐｌｉｃａｔｉｏｎｓｉｎｍａｇｎｅｔｉｃｒｅｃｏｒｄｉｎｇ,ｆｅｒｒｏｆｌｕｉｄｓ,ｍｅｄｉｃａｌｄｉａｇｎｏｓｔｉｃｅｔｃ..Ｔｈｅｍａｇｎｅｔｉｃｐｒｏｐｅｒｔｉｅｓｏｆｆｉｎｅｐａｒｔｉｃｌｅｓｄｉｆｆｅｒｍａｇｎｉｆｉｃｅｎｔｌｙｆｒｏｍｔｈｏｓｅｏｆｌａｒｇｅｐａｒｔｉｃｌｅｓ,ａｎｄｔｈｅｒｅｌａｔ…     

RFe7Mn4Ti化合物的结构和磁性(R=Y,Tb,Dy,Ho,Er)

研究了Mn部分替代RFe11Ti中的Fe对化合物结构和磁性的影响 .利用真空电弧熔炼和真空热处理制备RFe7Mn4 Ti(R =Y ,Tb ,Dy ,Ho和Er)化合物样品 .室温粉末样品的X射线衍射和热磁曲线测量表明 :所有这些化合物都具有单ThMn12 型结构 ,且具有良好的单相性 ,其晶格常数和单胞体积随着稀土元素的不同而变化 .在DyFe7Mn4 Ti和HoFe7Mn4 Ti化合物的热磁曲线上出现了明显的补偿特征 ,补偿温度分别约为 12 3K和 90K .同时给出了这些化合物的居里温度、饱和磁化强度及每单位分子式的饱和磁矩 .     

二重Cavley树上自旋为1／2和3／2的混合自旋模型的亚铁磁性质

利用迭代方法,在亚铁磁情况下,研究了晶体场作用下二重Cavlev树上自旋为1／2和3／2的混合Ising模型的热力学和临界现象。通过数值求解,得出了亚晶格磁化强度MA,MB和系统总磁化强度M随温度变化的曲线,并和铁磁情况所得结果进行比较。研究发现,子晶格B上的磁化强度MB随温度变化的趋势与铁磁情况下一致,而对于子晶格A来讲,磁化强度｜MA｜随温度变化的趋势与铁磁情况下一致,同时得出总磁化强度M的变化趋势与亚晶格磁化强度MA的变化一致,而且配位数对MB的随温度变化的曲线产生影响。结果发现,亚铁磁情况下该系统不存在三临界行为。     

甲醇摩托发动机高能点火互感电路过渡过程研究及仿真分析

提出一种研究高能点火互感电路过渡过程的新方法。通过对磁介质磁化曲线采用数理统计方法拟合，找出拟合函数，然后运用四阶龙格－库塔法求解微分方程。文中求出初级电流瞬态解，同时给出PSPICE软件仿真结果。     

饮用水消毒技术的回顾与展望

饮用水消毒技术是我国目前城市给水工程面临的一道难题。文章介绍了传统的氯消毒工艺的现状及存在问题，提出于改进方法，并探讨了其它的一些消毒工艺。     

MAGNETIC PROPERTIES OF TWO DIMENSIONAL ISING ANTIFERROMAGNET-ANTIFERROMAGNETIC SUPERLATTICE

An effective-field treatment for the two dimensional Isingantiferromagent-antiferromagnetic superlattice(AFAFS)without external field is pres-ented.The critical temperature dependence of the number of laycrs of superlattice cell andthe temperature dependence of magnetization of each layer in the superlattice are investi-gated.The similarity of the magnetic properties of AFAFS and those offerromagnet-ferromagnetic superlattice(FFS)is also discussed.