微波谐振腔Q值对磁激子振幅不稳定态阈值的影响

基于Safonov和Yamazaki所发展的激励自旋波非线性辐射衰减的理论［J. MMM. 161 (1996 ) 275］, 考虑磁激子与磁激子以及磁激子与光子的两种非线性相互作用过程，计算了微波谐振腔Q值对磁激子振幅不稳定态阈值的影响，结果与实验数据基本一致. 关键词： 磁激子 谐振器 铁磁体     

静磁场中的互作用能

讨论了在激发磁场的电流保持不变时和束缚磁荷作为磁场的不变时，两种情况下磁场的相互作用能。结果与静电场类似，两种情况的互作用能中都含有相互磁化，致使物体磁化状态改变作的功。     

Moessbauer Investigation of the Ferromagnetic Coupling in Copper-Iron Polycyanides

One of the Prussian blue analogs, molecular magnet Cu3^Ⅲ [Fe^Ⅲ (CN)6]2.11.6H2 O, was investigated by Moessbauer spectroscopy. It was found that transition temperature was around Tc = 18.5 K from paramagnetic phase to ferromagnetic phase. The β value of the critical exponent is around 0.338 at magnetic ordering temperature.Therefore, the ferromagnetic coupling interaction of Cu-Fe cyanide could be clearly explained by spin wave theory.     

具有特殊电子性能的有机固体

本文综述了具有特殊固体电子性能(导电性、铁磁性和非线性光学性质)的有机晶体和高分子化合物的合成、结构和性质,重点在于介绍结构与性能的关系以及这些研究领域的最新进展。     

铁磁性过渡离子掺杂对纤锌矿相硫化锌电子结构的影响

通过第一性原理计算,优化了铁磁性过渡离子掺杂的纤锌矿相硫化锌Fm0.125Zn0.875S(Fm=Fe、Co、Ni)的几何结构,计算了其电子结构,分析了其半金属性及其微观机制。结果表明:对不同的铁磁性杂质离子,Fm0.125Zn0.875S在费米面处的自旋极化率均为-100%,具有半金属性,是潜在的优质自旋注入材料。Fm0.125Zn0.875S具有较宽的自旋带隙,从而具有较高的居里温度和广泛的应用前景。Fe0.125Zn0.875S、Co0.125Zn0.875S和Ni0.125Zn0.875S的2×2×1超胞的磁矩分别为3.96μB、2.90μB和2.00μB,主要来自于铁磁性过渡离子Fe、Co和Ni离子。这3种离子的电子结构分别为eg2↑eg1↓t2g3↑,eg2↑eg2↓t2g3↑和eg2↑eg2↓t2g3↑t2g1↓。     

Zero—field—cooled and field—cooled magnetizations and magnetic susceptibility of itinerant ferromagnet SrRuO3

Zero-field-cooled(ZFC) magnetization,field-cooled(FC) magnetization,ac magnetic susceptibility and major hysteresis loops of itinerant ferromagnet SrRuO3 have been measured at magnetic ordering temperatures ranging from 5 to 160K.An empirical model is proposed to calculate the measured ZFC magnetization.The result indicates that the calculated ZFC magnetization compares well with the measured one.Based on the generalized Preisach model.both the ZFC and FC curves are reproduced by numerical simulations.The critical temperature and critical exponents are determined by measuring the ac magnetic susceptibility in different bias magnetic fields at temperatures in the vicinity of the point of phase transition.     

Quantum Phase Transition and Ferromagnetic Spin Correlation in Parallel Double Quantum Dots

We investigate electronic transport through a parallel double quantum dot （DQD） system with strong on-site Coulomb interaction, as well as the interdot tunnelling. By applying numerical renormalization group method, the ground state of the system and the transmission probability at zero temperature are obtained. For a system of quantum dots with degenerate energy levels and small interdot tunnel coupling, the spin correlations between the DQDs is ferromagnetic, and the ground state of the system is a spin-1 triplet state. The linear conductance will reach the unitary limit （2e^2/h） due to the Kondo effect at low temperature. As the interdot tunnel coupling increases, there is a quantum phase transition from ferromagnetic to anti-ferromagnetic spin correlation in DQDs and the linear conductance is strongly suppressed.     

费密液体和自旋液体的混合体——一种描述高温超导体中电子状态的理论模式

 本篇系特约稿,由著名超导专家赵忠贤教授审阅,特表谢意.作者熊诗杰,46岁,南京大学物理系研究员.1968年毕业于北京大学,1983年获得南京大学博士学位,1988-1990年先后在英国剑桥大学超导研究中心、美国休斯敦大学德克萨斯超导中心进行访问研究.1991年被国务院学位委员会及国家教委授于“有突出贡献的中国博士”荣誉称号,还被美、英等国名人中心收入三个国际名人录.已在国内外有影响学术刊物发表论文70余篇.     

准一维有机铁磁体的磁性机理研究

对准一维有机铁磁体ｐｏｌｙ－ＢＩＰＯ体系的磁性机理进行了研究。详细考虑了该体系中的电子跳跃、电子关联及派尔斯不稳定性，自洽地计算了其能带结构和自旋密度分布，并数值地研究了各因素对系统特性的影响。结果发现该体系基态为稳定的铁磁态． 关键词：