PLD growth of stoichiometric Fe/sub 3/O/sub 4/ thin films for spin tunneling devices

Epitaxial thin films of Fe/sub 3-/spl delta//O/sub 4/ were prepared on [100] MgO substrates by pulsed laser deposition. These films had a smooth surface on an atomic scale along with extremely high crystalline quality. It was found from the resistivity and XPS measurements that thin films of nearly stoichiometric Fe/sub 3/O/sub 4/ are obtained at 300/spl deg/C in oxygen pressure of 1/spl times/10/sup -6/ Torr and the conditions for growing the stoichiometric Fe/sub 3/O/sub 4/ thin film lie in a narrow range. In addition, it was indicated that low temperature deposition below 200/spl deg/C is required for the insulating oxide layer onto the Fe/sub 3/O/sub 4/ layer in the fabrication process of the tunneling junctions even at oxygen pressure as small as 1/spl times/10/sup -5/ Torr.