Cobalt silicide formations and magnetic properties of laser ablated Co(Cr) thin films

The solid-phase reaction between Si(111) substrate and the Co(Cr) films produced by laser ablation at temperatures ranging from 400 °C to 600 °C, as well as their magnetic properties were investigated. It has been shown that the Co films consist of CoSi(111) phase during 500-600 °C and co-existed CoSi and CoSi2 silicides at 600 °C by X-ray diffraction and transmission electron microscopy. However, the deposited CoCr22 films contain only CoSi phase with (111) preferential orientation at deposited temperature from 500 °C to 600 °C, suggesting that the Cr element may act as a diffusion barrier in the CoCr/Si system. The magnetic coercivity and squareness of the produced films decrease as the deposited temperature increases and it almost cannot be detected at 600 °C. Adding Cr element into the Co films can improve and adjust the magnetic properties. The theoretical explanations of preferential orientations of CoSi(111) and CoSi2(200) have been given by comparing the arrangement of atoms on CoSi(111) and CoSi2(200) with that on Si(111).