Interface engineering using an Fe oxide insertion layer for growing a metastable bcc-Co on MgO(001)

摘要

We report a technique to form a high quality bcc-Co thin film on MgO by inserting an ultrathin γ-Fe_2O_3 layer. An ultrathin Co layer directly grown on MgO takes the well-known island growth mode, while the insertion of an ultrathin γ-Fe_2O_3 layer thicker than 0.2 nm provides a clear improvement in the crystalline quality even for 1.0 nm thick Co. Additionally, a metastable bcc-Co layer was obtained when the thickness of the γ-Fe_2O_3 layer was increased up to 0.4 nm. Owing to the morphological improvement, even the 0.6-nm-thick Co layer exhibited ferromagnetic hysteresis curves with high remanence. The interface engineering developed here offers increased flexibility in the structural design for spintronic devices.