Bias dependence of the tunneling magnetoresistance in double spin-filter junctions

With the intention of providing reference materials for research, manufacture and application of magnetoresistance devices, we calculate the dependences of tunneling magnetoresistance (TMR) in a NM/FI/FI/NM. double spin-filter junction (DSFJ) on the bias (voltage) and, secondarily, on the thickness, barrier height and molecular field of FIs [here the NM and FI-represent the nonmagnetic electrode and the ferromagnetic insulator (semiconductor) spacer, respectively]. Our results show that for the TMR of the DSFJ besides its very high value it does not decrease monotonously and rapidly with a rise of bias, but increases slowly at first and then decreases after a maximum value is reached. This feature is in distinct contrast to the ordinary magnetic tunnel junction FM/NI/FM and thus facilitates the application of the DSFJ as a magnetoresistance device [here FM and NI denote the ferromagnetic electrode and the nonmagnetic insulator (semiconductor) spacer, respectively]. The influence of the thickness, barrier height and, especially, the molecular field of FIs on TMR and its bias dependence is also not negligible. (C) 2003 American Institute of Physics.