Magnetic properties of oxygen exposed on the ultrathin Co/Ge(1 1 1) films have been investigated by surface magneto-optic Kerr effect (SMOKE). After being exposed on the 15-30 monolayers (ML) Co/Ge(1 1 1) films, the oxygen atoms only distribute on the topmost layer of Co films. The oxygen layer influences the electronic density of states of Co only on the topmost layer and leads to reduction in the saturated magnetization. Besides, the appearance of the Co/O interface forms additional interfacial anisotropy; consequently, coercivity of ultrathin Co/Ge(1 1 1) film is enhanced. As an example for 15 ML Co/Ge(1 1 1), the coercivity increases from 730 to 920 Oe with 200 L of oxygen exposure. Besides, the film with thinner Co layer exhibits stronger coercivity enhancement effect after exposing 200 L oxygen.
- Co/O interface
- Surface magneto-optic Kerr effect
- Ultrathin magnetic film
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics