Transmission Electron Microscopy Study of the Fe(001) $\vert$ MgO(001) Interface for Magnetic Tunnel Junctions

Transmission electron microscopy (TEM) is employed to characterize ex situ the interface between the bottom Fe (001) electrode and MgO (001) barrier in a magnetic tunnel junction (MTJ) deposited by molecular beam epitaxy. High resolution TEM images are compared with multislice-based simulations of oxidized and sharp interfaces to conclude that at least the part of the interface is not oxidized. In addition, the spacing between the Fe and O layers at the interface is measured and found to be comparable with theoretical calculations in the literature of sharp interfaces. This result offers a methodology to characterize the interface structure of MTJs, which is important to determine the magneto-transport properties of the device