Electron-Electron Interaction Effects in Magnetic Tunneling Junctions

✍ Scribed by Du, J. ;Landry, G. ;Xiang, X.H. ;Xiao, J.Q.

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 119 KB
• Volume: 189
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/1521-396x(200202)189:2<559::aid-pssa559>3.0.co;2-t

✦ Synopsis

By oxidizing wedge-shaped Al films we have fabricated magnetic tunneling junctions with over-, complete, and under-oxidized barriers. By investigating the capacitance spectra, we are able to study the effects due to interface charge accumulation. The electron-electron interaction among accumulated interface charges leads to a voltage drop inside the magnetic electrodes, resulting in the measured capacitance differing from the geometric capacitance. We have extracted an interfacial capacitance of 16 mF/cm 2 per interface and a screening length of 0.55 A for FeNi electrodes. We also observed some interesting phenomena in bias dependence of TMR along the wedge. Bias curve of MR is asymmetric in over-oxidized, and symmetric in under-oxidized regions. These behaviors have been explained using a model based on charge accumulation effect at the metal-insulator interfaces.