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, Co films (≤10 monolayers) with in-plane easy axis of magnetization have been successfully prepared. At the Si substrate temperature of 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 300K. However, their thicknesses were reduced to 1.4 monolayers when deposited at 120 K.