Abstract:

The Cr/Gd bilayer was deposited by magnetron sputtering method, where the Curie temperature T_C of the ferromagnetic Gd layer was less than the Néel temperature T_N of the antiferromagnetic Cr layer. The temperature dependence of the magnetic properties of the film was characterized by means of vibrating\|sample magnetometer (VSM). It was shown that the Cr/Gd bilayer exhibited quite different behaviors from those of the FM/AFM bilayers with T_C＞T_N. We have observed that the Gd layer persisted in the ferromagnetic phase even at T＞T_C. The coercivity H_C of the film does not vary monotonously with temperature. H_C decreases with  temperature increase in a temperature range of 80~205 K, exhibiting a minimum value at T=205 K, and then goes up until reaching a peak at T=255 K, at 255 K＜T＜295 K, the coercivity decreases sharply with  temperature, when T＞295 K, however, H_C increases with  temperature increase. The experimental results indicate that the magnetic ordered temperature and coercivity of the ferromagnetic layer are strongly influenced by the interfacial exchange coupling between the Gd and Cr layers.

Key words: ferromagnetic/antiferromagnetic film, coercivity, exchange couping, Cr/Gd bilayer