Double Tunnel Junction Experiments With Asymmetric Barriers*

Magnetic tunnel junctions constitute a research area of great promise due to its potential application in faster and non-volatile memories. Current studies on Magnetic Tunnel Junctions (MTJ) are abundant for different magnetic and insulator materials. Nevertheless, available references for Double Magnetic Tunnel Junctions (DMTJ) are scarce. Previous studies on Tunneling Magnetoresistance (TMR) Oscillations in DMTJ indicate that asymmetry in the potential barriers is a significant aspect for controlling the TMR.
In the present work we show the fabrication of Al/ Al₂O₃/ Al/ Al₂O₃/ Al double tunnel junctions with asymmetric barriers by e-beam evaporation and oxygen plasma processes in UHV chamber. The experimental process allows us to characterize each of the junctions separately. This way the parameters, width and thickness, were easily extracted for each of the junctions, prior to be used in a model for double tunnel junctions.