Growth of a High-Quality Ultrathin Fe(001) Layer on MgO(001) by Insertion of an Ultrathin ?-Fe2O3 Layer

We have successfully developed a technique to obtain atomically flat ultrathin Fe(001) layers on MgO(001). In contrast to the usual island morphology of ultrathin Fe layers grown directly on MgO(001), the insertion of an ultrathin g-Fe2O3 layer improves the crystalline quality and interface flatness of the ultrathin Fe layer of less than 1 nm thick. Owing to the continuous layered structure, even 0.6-nm-thick Fe layers exhibited a ferromagnetic hysteresis curve with high remanent magnetization. The technique enables flexible structural design of spintronic devices with ultrathin ferromagnetic electrodes.