体极化子的类相变行为

本文将电子的动量和位置的线性组合作为算符,应用了Bogolyubov不等式,并对哈密顿量进行两次么正变换,对电子-声子耦合常数α的整个区域和温度的尽可能广泛范围计算了体极化子的基态能量,有效质量及电子周围的平均声子数。发现对应一定的温度,当α超过一定值αc 时,极化子将发生相变。并且本文还找到了一个临界温度Tc ,当温度大于Tc 与温度小于Tc 时其相变行为是不同的。     

MAGNETIC PROPERTIES OF BALL MILLED FexCu1-x (x=0.4, 0.5) ALLOY

The samples Fe_0.4Cu_0.6 and Fe_0.5Cu_0.5 ball milled for 50 h are investigated by X-ray diffraction, M?ssbauer spectra, as well as magnetic measurement. The experiments show that the structure of the samples is fcc, with lattice constant 0.361 nm and there are fcc Fe-rich phase and fcc Cu-rich phase in the samples. Most of Fe atoms (91%) are in the fcc Fe-rich phase, which is a ferromagnetic phase. The M-H curve at 1.5 K shows the saturation magnetization of the samples are 80.5 emu/g and 101.6 emu/g for Fe_0.4Cu_0.6 and Fe_0.5Cu_0.5 respectively. The average magnetic moment of Fe atoms is deduced to be 2.40 μ_B . Compared with theoretical predication, the Fe atoms in the fcc phase are in high spin state.