Effect of Spin Fluctuations on Magnetic Properties and Thermal Expansion in Pseudobinary System Fe_xCo_1−xSi

抄録

Both magnetization and thermal expansion measurements have been made on the same samples of Fe_xCo_1−xSi alloys. The magnetization data is analyzed on the basis of the spin fluctuation theory developed by Takahashi to obtain information on the nature of spin fluctuations of this system. We found that concentration variation of magnetic behaviors of the ferromagnetic alloys, such as the Arrott plots and the temperature dependence of spontaneous magnetization, is quantitatively well explained by the theory. Magnetovolume coupling constant is also estimated from thermal expansion coefficient on the basis of the SCR theory over the wide concentration range. The magnetovolume effect is also in good accordance with the predictions of Takahashi’s theory, even quantitatively.