Formation of the Co/Si(110) interface: Phase composition and magnetic properties

The formation of the Co/Si(110)16 $\times$ 2 interface and its magnetic properties are studied by high-energy-resolution photoelectron spectroscopy using synchrotron radiation and magnetic linear dichroism in the photoemission of core electrons. It is shown that a cobalt coating less than 7 $\mathring{\mathrm{A}}$ thick deposited on the silicon surface at room temperature results in the formation of an ultrathin (1.7 $\mathring{\mathrm{A}}$) interfacial cobalt silicide layer and a layer of silicon-cobalt solid solution. The ferromagnetic ordering of the interface is observed at an evaporation dose corresponding to 6–7 $\mathring{\mathrm{A}}$ in which case a cobalt metal film begins to grow on the solid solution layer. During 300$^\circ$C-annealing of the sample covered by a nanometer-thick cobalt layer, the metal film gradually disappears and four silicide phases arise: metastable ferromagnetic silicide Co$_3$Si and three stable nonmagnetic silicides (Co$_2$Si, CoSi, and CoSi$_2$).