Temperature dependence of site-resolved Fe magnetic moments in ThMn12-type Sm(Fe1−Co )12 compounds studied via synchrotron Mössbauer spectroscopy

The relationship between the magnetization and magnetic moment at each Fe site in Sm(Fe _{1− x}Co _x) ₁₂ compounds and their temperature dependence were investigated via synchrotron Mössbauer spectroscopy. The enhancement in the Fe magnetic moments in the Sm(Fe _{1− x}Co _x) ₁₂ compounds with increasing Co content was observed at a similar rate as the increment in their saturation magnetization at 300 K. We found that the magnitudes of the Fe magnetic moments vary in a descending order: 8i > 8j > 8f, and they are independent of the Co content because the variation is caused by the magneto-volume effect. The curvatures of the temperature dependence of the Fe-sublattice magnetic moments are larger and also vary in the order of 8i > 8j > 8f because the enhancements in the exchange coupling strength decrease in the same order.