Hi, I developed a model to calculate the TMR of NGN MTJ as attachments showed and got results as follows,
Conductance Parallel Spin (Siemens)
Up=1.98e-05, Down=4.09e-05
Total = 6.08e-05
Conductance Anti-Parallel Spin (Siemens)
Up=2.20e-05, Down=2.20e-05
Total = 4.39e-05
TMR (optimistic) = 38.35 percent
TMR (pessimistic) = 16.09 percent
when I add double gates into the model and the gate voltages are both set to 0V, I get results like this,
Conductance Parallel Spin (Siemens)
Up=3.29e-05, Down=3.82e-05
Total = 7.11e-05
Conductance Anti-Parallel Spin (Siemens)
Up=3.12e-05, Down=3.12e-05
Total = 6.23e-05
TMR (optimistic) = 14.10 percent
TMR (pessimistic) = 6.59 percent
Maybe the absence of periodic boundary of the model caused the decrese of TMR, so I increase the width of the graphene barrier to get a TMR that closer to 38%. However, I get a result like this,
Conductance Parallel Spin (Siemens)
Up=4.80e-05, Down=5.79e-05
Total = 1.06e-04
Conductance Anti-Parallel Spin (Siemens)
Up=5.34e-05, Down=5.34e-05
Total = 1.07e-04
TMR (optimistic) = -0.86 percent
TMR (pessimistic) = -0.43 percent
I just simply increased the barrier width, and got a negative TMR, what is the problem? Is the model improper? The model is in the attachment, need your help, thanks for your time.
