Improving MgO/Fe insulator-metal interface structure through oxygen-precoating of Fe(001)

We grew atomically fiat and electronically uniform MgO island terraces on a Fe(0 0 1) whisker substrate precoated by a p(1 x 1) oxygen monolayer film. This interface engineering process increased about 10 times the size of MgO islands compared to the size of MgO islands directly grown on Fe(0 0 1), showing that the interface oxygen monolayer plays an essential role in MgO growth. Importantly, each squared-shape atomically fiat MgO island includes only a few atomic defects, which provides high-quality insulating layers. Further, the MgO islands have an electronic decoupling functionality from the metal substrate. Surface morphology and local electronic structures were studied using a home-built ultrahigh vacuum scanning tunneling microscopy (STM) at a temperature of 5 K.

Automated summary

It was found that atomically flat and electronically uniform MgO island terraces could be grown on a Fe(0 0 1) whisker substrate precoated by a p(1 x 1) oxygen monolayer film. The interface oxygen monolayer played an essential role in promoting the growth of MgO islands, resulting in a ten-fold increase in their size compared to those directly grown on Fe(0 0 1). The atomically flat MgO islands exhibited only a few atomic defects, making them suitable for high-quality insulating layers. Additionally, the MgO islands showed electronic decoupling functionality from the metal substrate. Surface morphology and local electronic structures were investigated using a home-built ultrahigh vacuum scanning tunneling microscopy (STM) at 5 K.