Theory of tunneling magnetoresistance and tunneling electroresistance in Co/BiFeO3/La2/3Sr1/3MnO3 junctions
Journal
Journal of Applied Physics
Journal Volume
104
Journal Issue
5
Date Issued
2008
Author(s)
Abstract
We present a theory of tunnel magnetoresistance (TMR) and tunnel electroresistance (TER) in multiferroic Co/BiFeO3/La2/3Sr1/3MnO3 junctions. Both the half-metallic band structure of the La2/3Sr1/3MnO3 electrode and the multiferroicity in the BiFeO3 barrier are considered explicitly in our model. Using transfer matrix method, we have derived an analytic formula for TMR in these structures. The calculations indicate that TMR is larger when the electric polarization in BiFeO3 points to half-metallic La2/3Sr1/3MnO3 and that the thicker the barrier is, the larger is the TMR, while for the negative electric polarization, the thicker the barrier is, the smaller is the TMR. In the mean time, the weak ferromagnetism, arising from spin-orbit coupling in BiFeO3, is found to give a further variation of TMR and TER in these structures. These results agree with recent experimental observation well.
Type
journal article