Spin-dependent Transport In Ferromagnetic/semiconductor/ferromagnetic Junctions

Based on Sloczewski free electrons model, considering spin filtering effect and the Rashba spin-orbit interaction, in quantum coherent ballistic transport,we investigate transport properties of spin-polarized electrons tunneling through ferromagnetic/insulator/ferro- magnetic conductor/insulator/ferromagnetic junction.The insulator in this work is a finite length layer,not a Delta potential.In this paper,we deduce a formula of the transmission coefficient using the tansfer matrix method for the double tunnel junction and investigate the transport properties vs the Rashba spin-orbit coupling strength,the length of the ferromagnetic semiconductor, spin filtering effect,and the length of the insulator.The resuts of the numerical calculation indicate that:Tunneling coefficient, spin polarization and tunneling magnetic resistance oscillate with the Rashba spin-orbit coupling strength,the length of the ferromagnetic semiconductor,and the length of the ferromagnetic semiconductor.We can get higher tunneling magnetic resistance through ferromagnetic/insulator/ferro- magnetic conductor/insulator/ferromagnetic junction than ferromagnetic/insulator/ferromag- netic conductor/insulator/ferromagnetic junction.When both layer thickness,and the magnetizing direction of ferromagnetic semiconductor layers parallels to left ferromagnetic layers,the tunneling magnetic resistance is obviously improved than erromagnetic/insulator/ferromagnetic conductor/insulator /ferromagnetic junction, increased by 20%.Insulation potential barrier in low altitude, tunneling coefficient, spin polarization and tunneling magnetic resistance increases with potential highly.With the Insulation potential barrier continuous increase they begin to oscillate.But when a barrier to a certain height, tunneling coefficient sharply to 0.