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Based upon the spin wave theory, the influence of the size of a three-dimensional Heisenberg system on its thermodynamic properties was studied. It is found that the specific heat increases due to the finite size and free surface of the system. For a magnetic film with finite thickness, the interaction of spin waves was also discussed. There exist three additional scattering processes, namely, the scattering between spin waves with wave-vectors parallel to the surface of the film (two-dimensional spin wave), the scattering between two and three-dimensional waves, and the scattering between those waves with the same component in the direction along the thickness of the film. As a result, the T4 term, arising from the coupling of spin waves, in the expression of the specific heat of the system, splite into three parts proportional to T5/2,T7/2 and T4, respectively. Here T is the temperature. 相似文献
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We extend the hole confinement model of Edwards et al. to the problem of two kinds of complex magnetic sandwich structures. One is the magnetic sandwich covered on both sides by nonmagnetic films(case 1) and the other is that covered by magnetic films(case 2). The interlayer exchange coupling and the angular dependence of coupling energy in the two cases are investigated systematically. For case 1, our results show that the magnetic and outer nonmagnetic films influence significantly the oscillation behavior of exchange coupling and the appearance of noncollinear exchange coupling is very sensitive to the thickness of magnetic and outer nonmagnetic layers. Our results also show that the nonoscillatory component of the coupling generally varies with the thickness of magnetic(outer nonmagnetic) films and the results in the case where the thickness of both magnetic(outer nonmagnetic) films vary simultaneously are significantly different from that in the case where the thickness of one of the two magnetic(outer nonmagnetic) films is fixed while the other is varied, which is qualitatively in agreement with the experimental measurements. For case 2, the exponential dependence of exchange coupling on the thickness of the intermagnetic layer has been obtained, similar to the Parkin's experimental results for giant magnetoresistance. 相似文献
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在整个中华民族蒙灾受难的“十年动乱”中 ,我国物理学也遭受了种种损失 .2 0年前 ,已经初露锋芒的青年实验物理学家和热忱的科学组织者孟宪振同志含冤离去 ,就是至今思之犹痛的损失之一 .孟宪振 ,1931年生于北平 ,194 9年考入清华大学气象系 ,1952年从物理系毕业后分配到中国科学院应用物理研究所 (后改称物理研究所 ) .1953年我国开始实行第一个国民经济五年计划 ,全国上下都在为开展大规模的经济建设而奋斗 .应用物理研究所集中主要力量 ,解决经济建设提出的迫切课题 .孟宪振等在前辈磁学家施汝为、潘孝硕、向仁生指导下 ,参加铝镍钴磁性… 相似文献