抗磁质的磁化机理

本文从讨论抗磁质分子磁矩的构成出发,重点分析外磁场使电子轨道角速度发生变化,因而改变轨道磁矩,使激发的抗磁质分子磁矩方向与外磁场方向相反。最后对超导体抗磁效应的特点作了简要的说明。这篇文章是作者在教学中处理教材的一点体会。     

Analysis of magnetic mechanisms of 3d-doped ZnO diluted magnetic semiconductors by an abnormal peak on M-T curve

The crystallographic structures and magnetic properties of a Zn0.95Co0.05O thin film deposited on a C-sapphire substrate using a dual-beam pulsed laser deposition method were characterized. It was shown from crystallographic analysis that the film belongs to the wurtzite structure with the C-axis aligned with that of the substrate. Magnetic hysteresis loops were observed till up to room temperature. A small peak around 55 K was noticed on the magnetization vs. temperature curve. The corresponding temperature of the small peak is close to that of ‘the abnormal peak’ reported by X.M. Zhang et al. From the results obtained, no correlation was found between the abnormal peak and the quantum effects. The magnetic behaviors in the Zn0.95Co0.05O film cannot be explained by the ferromagnetism in diluted magnetic semiconductors. The magnetic mechanisms in ZnO-based diluted magnetic semiconductors are also discussed.     

顺抗磁性混合气体在梯度磁场中流动的蒙特卡罗直接模拟

以氧气和氮气的混合气体为研究对象,运用蒙特卡罗直接模拟方法模拟了顺抗磁性混合气体在高梯度磁场中的流动情况,并把模拟计算结果与已有的实验结果之间进行了对比分析. 模拟结果表明:磁场强度与梯度乘积由100T2·m-1增加到1000T2·m-1时,氧体积分数增量由0.12%增加到1.89%;混合气体温度由283K升高到333K时,氧体积分数增量由0.4%减小到0.1%;混合气体中氧气的初始体积分数由20%增加到30%时,氧体积分数增量由0.12%增加到0.59%;压力的变化对氧体积分数的变化几乎没有影响.     

二维含铁磁耦合费米气体磁学性质的研究?

在平均场理论的框架下,推导出外磁场中具有铁磁耦和作用的二维费米气体的自洽方程,在此基础上,运用量子统计力学研究系统的磁学性质.结果表明总磁化强度密度随磁场强度的增大会出现极大值点,且随铁磁耦合强度增大,极大值点向磁场减弱的方向移动.总磁化强度密度也随Lande因子的增大,发生由抗磁性向顺磁性的转变.