Fe/Si(001) Ferromagnetic Layers: Reactivity, Local Atomic Structure and Magnetism

Ultrathin ferromagnetic Fe layers on Si(001) have recently been synthesized using the molecular beam epitaxy (MBE) technique, and their structural and magnetic properties, as well as their interface reactivity have been investigated. The study was undertaken as function of the amount of Fe deposited and of substrate temperature. The interface reactivity was characterized by Auger electron spectroscopy (AES). The surface structure was characterized by low‐energy electron diffraction (LEED). The magnetism was investigated by magneto‐optical Kerr effect (MOKE). A higher deposition temperature stabilizes a better surface ordering, but it also enhances Fe and Si interdiffusion and it therefore decreases the magnetism. Despite the rapid disappearance of the long range order with Fe deposition at room temperature, the material exhibits a significant uniaxial in‐plane magnetic anisotropy. For the Fe deposition performed at high temperature $(500 °C),$ a weak ferromagnetism is still observed, with saturation magnetization of about 10% of the value obtained previously. MOKE studies allowed inferring the main properties of the distinct formed layers.