Fabrication and characterization of magnetic tunnel junctions with L10-ordered FePt alloy electrodes

The multiple oxidation process was applied to AIO barriers in order to improve barrier properties and room temperature-magnetoresistance in magnetic tunnel junctions (MTJ) with L1₀-FePt electrodes. The L1₀-FePt bottom electrodes were prepared by UHV magnetron sputtering with a shadow mask. Fe seed layer and Au buffer layer were deposited at room temperature on MgO(110) single crystal substrates. AlO barriers were formed by the multiple oxidation process with a magnetron sputtering apparatus. A Fe₅₀Co₅₀ top electrode was deposited to complete the L1₀-FePt/AlO/FeCo cross-patterned MTJ geometry. The structural characterization of the MTJ was performed by X-ray diffraction (XRD), RHEED and AFM. Magnetic properties were measured by a SQUID magnetometer. Magnetotransport properties, such as tunneling magnetoresistance (TMR) and current-voltage (I-V) characteristics, were measured by a dc four-probe method. The improved TMR ratios at room temperature indicate that the multiple oxidation process is useful to improve the magnetotransport properties of MTJs with L1₀-FePt electrodes.