Eur. Phys. J. B 31, 463-469 (2003)
https://doi.org/10.1140/epjb/e2003-00056-0

Analytical result of the effect of spin scattering and impurity-assistance on magnetoresistance in doped magnetic tunneling junctions

¹ Department of Physics, Nanjing Normal University, Nanjing 210097, PR China
² National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, PR China

Corresponding author: ^a yctao12@163.com

Received: 13 January 2002
Revised: 30 November 2002
Published online: 6 March 2003

Abstract

An extended tunneling Hamiltonian method is proposed to study the temperature-dependent tunneling magnetoresistance (TMR) in doped magnetic tunnel junctions. It is found that for nonmagnetic dopants (Si), impurity-assisted tunneling is mainly elastic, giving rise to a weak spin polarization, thereby reduces the overall TMR, while for magnetic ions (Ni), the collective excitation of local spins in δ-doped magnetic layer contributes to the severe drop of TMR and the behavior of the variation of TMR with temperature different from that for Si-doping. The theoretical results can reproduce the main characteristic features of experiments.