THERMOMAGNETIC EFFECT OF THE Sm-T(T = Fe, Co ) AMORPHOUS THIN FILMS IN HIGH FIELDS

The temperature dependence of magnetization at H=0.1-7T for amorphous Sm x T 1-x (T = Fe, Co) thin films was investigated in the range of 1.5 to 300 K. It was found that there was a maximum magnetization in the σ(T) curves, measured in the temperature rising process, for the Sm x Co 1-x thin films (x=0.46, 0.48, 0.54, 0.65). For the Sm-Co alloys, the temperatures, corresponding to σ max , are about 25-28 K and are independent of the composition. But the Sm-Fe amorphous alloys are different from the Sm-Co alloys, in the former the temperature corresponding to σ max depends on both the field and the composition of the alloys. In addition, it was found that there was σ min (or a repaid variation) at T≈6 K, and σ(T) decreased very slowly near room temperature. It was suggested that the thermomagnetic effect for the Sm-Co thin films at high field may be caused by the contribution of Sm moment to the magnetization, though the magnetic moment of Sm atoms is very small (≈0.1μB), and the random local anisotropy is strong at low temperatures and changes signicantly between 20-30 K. But the thermomagnetic effect of the Sm-Fe amorphous alloys may be caused by the dispersion of the Fe moments. The σ min at T≈6 K and the slow decrease of σ(T) near room temperature may be caused by fluctuation of composition in these alloys.