Spin-polarized Transport in Magnetic Tunnel Junctions

We focus on the interfacial issue in MTJs. MTJs are fabricated by depositing a wedge-shaped Al layer. Subsequent oxidation of this layer provides over, complete, and under -oxidized alumina barriers. Various physical parameters can thus be related to interfacial properties. We also study the electron-electron interaction effects due to accumulation of charge and magnetization at the interface, from which electron screening length, spin diffusion length, and capacitance of MTJs can be studied.
The characteristic length scale for electron contribution to spin polarized transport has also been investigated. The concept of ballistic spin diffusion has been proposed from our experimental results.

Sample publications:
1. G. Landry, X.Xiang, Y. Dong, and John Q. Xiao, " Interfacial Capacitance Effects in Magnetic Tunneling Junctions", Appl. Phys. Lett. 78, p501 (2001).
2. L. Ritchie, X. Liu, S. Ingvarsson, G. Xiao, J. Du, and John Q. Xiao, "Large Exchange Bias Through Seed Layer Variation in NiFe/Al2O3/NiFe Tunnel Junctions", to appear in Appl. Phys. Letts. (2001).
3. T. Zhu, X.H. Xiang, G. Landry, D.V. Dimitrov, N. Garcia, and John Q. Xiao, "Bulk versus Interface Contributions to TMR in Magnetic Tunnel Junctions", Submitted to Phys. Rev. Letts.