Atomic Layer Deposition of Magnetic Thin Films

We report on the research effort towards the development of processes for the realization of magnetic tunnel junctions by atomic layer deposition. Our strategy follows two main schemes. The first is a hybrid process where the ferromagnetic layers are produced by chemical vapour deposition and the tunnel oxide is deposited by atomic layer deposition. As ferromagnetic electrodes we use Co and $Fe_3O_4$, while MgO, $Al_2O_3$, and $HfO_2$ are employed as tunnel oxides. The second and most intriguing scheme is a full-oxide approach in which the ferromagnetic layers and the tunnel barrier layer are all oxides grown by atomic layer deposition. As ferromagnetic layers we focused on the growth of complex manganites $(La_{0.7}Sr_{0.3}MnO_3)$ while as a tunnel oxide we propose $La_2O_3$. Film composition has been studied with time of flight secondary ion mass spectroscopy and Rutherford backscattering spectrometry. X-ray diffraction, X-ray reflectivity, and Fourier transform infrared spectroscopy have been used to investigate the structure and morphology of the layers. The magnetic properties of the films are measured by superconducting quantum interference device magnetometer.