Cr/Gd双层膜的磁特性

Magnetic Properties of Cr/Gd Bilayers

采用磁控溅射法制备居里温度(TC)略低于奈尔温度(TN)的Cr/Gd双层薄膜.利用振动样品磁强计研究薄膜在不同温度下的磁滞特性.结果表明:该类薄膜系统与TC>TN的铁磁/反铁磁双层薄膜的磁滞特性不同,当测量温度(T)大于TC时,Gd层处于铁磁态,矫顽力(HC)随温度非单调变化;当T为80～205K时,HC随温度增加逐渐减小;在T=205K出现一个极小值后逐渐增大;在T=255K附近出现一个主峰;当T为255～295K时,HC随温度升高迅速减小;当T>295K时,HC随温度升高迅速增大.即铁磁/反铁磁界面处的反铁磁自旋与铁磁自旋的交换耦合作用对铁磁层磁有序态的维持温度和矫顽力影响较大.

The Cr/Gd bilayer was deposited by magnetron sputtering method, where the Curie temperature Tc of the ferromagnetic Gd layer was less than the NEel temperature TN 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 Tc 〉 TN. We have observed that the Gd layer persisted in the ferromagnetic phase even at T 〉 Tc. The coercivity Hc of the film does not vary monotonously with temperature. Hc 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, Hc 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.