Magnetic properties of ultrathin Co/Si(111) films

The orientation of magnetization and the thickness of the ferromagnetic inactive layer at the interface of Co film and Si substrate in an ultrathin Co/Si(111) film have been studied. At the Si substrate temperature of 120 K, Cu films (less than or equal to 10 monolayers) with in-plane easy axis of magnetization have been successfully prepared. At the Si substrate temperature or 300 K, ultrathin Co films (3.5-10 monolayers) with canted out-of-plane easy axis of magnetization were observed. The ferromagnetic inactive layers were formed at the interface due to the intermixing of Co and Si. and were 2.8 monolayers thick for Co films deposited at 300 K. However, their thicknesses were reduced to 1.4 monolayers when deposited at 120 K.