For the spin Polarization (Pol) equal 1, what's the difference of STT between P->AP and AP->P states for the same MTJ system?

[Hying]

Hi, 

when I set spin Polarization (Pol=1), I found that both the P->AP and AP->P states can finish the magnetization flipping. However, I confused that when Pol=1, in physical the reference layer of MTJ can only output the spin-polarized electrons in one direction (spin-up or spin-down) , then why both the cases (P->AP and AP->P states) can finish the magnetization flip? 

Thank you very much for the help!   

[Hying]

Hi everyone, 
please allow me to change the question that may be more clear: for the same STT-MTJ system, in order to simulate the magnetization flipping, for example Pol=0.4 is setting for P->AP state, what's value should I set Pol for AP->P state? 

Since at P->AP (AP->P) state, it's mainly the minority (majority) electrons join the spin angular moment exchanging. Pol value should be proportional to spin torque at AP->P state, but inverse ratio at P->AP? Also May somewhere I make a misunderstanding? 

Any help is appreciated! 

Thank you very much!