magnetic tunnel junction

[sahil]

dear all
i calculated the TMR for CoFe-mgo at different bias voltage. but my result seems to be incorrect because the conductance and current for both the configuration gives different values of TMR by formula

(Rap-Rp)/Rp and (Ip-Iap)/Iap
means in short it is not follow the ohm's law

i am not getting this difference please help me
and give me a idea for parallel resistance value for 6 atom thick barrier device with electrode length of 5.845A.(if you have)??

[Anders Blom]

They are supposed to be different. You can Google a bit about the "pessimistic" and "optimistic" definition of the TMR to learn more.

Besides, since when would you expect tunneling devices to follow Ohm's law? The fact that they don't is the whole point we do these calculations

[sahil]

I am really sorry for such mistake, infect i was confused by an paper in which it looks like to follow ohm's law
 ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5941929

thanks  

[sahil]

hiiii blom sir 
how can i find lattice mismatch between electrode and barrier layer using atk-vnl?
plz reply me  

[kstokbro]

In the new ATK12.2 there is an interface builder, which can automatically find the best supercell for describe the interface between two lattices

[sahil]

Thanks for your response 

[sahil]

Hello to all


Any one please tell me the use of preconditioner in iteration control parameter?


Thanks in advance for support 

[Anders Blom]

You probably don't need to use it. But more information can always be found in the reference manual.

[1ight0ne]

Hello! Can anyone tell me why TMR of structure Fe-MgO-Fe in examples is exceed 9000 % ? Does it normal and how it compare with experiment ? I saw the presentation about apply ATK in spintronics and TMR in this presentation about 2300 % What value of TMR is more correct?

[baizq]

Hi,

We may never expect the calculated TMR ratio (for Fe/MgO/Fe, several thousand percent) to be comparable to that in experiment (typically several hundred percent for (Co)Fe/MgO/(Co)/Fe). There're also quite a lot of computational work trying to explain the deviation, say, PRL 105, 236801 (2008).

The calculated MR ratio also depends on the model you use, for instance, how many MgO layers there are. TMR would differ a lot w.r.t. different number of MgO layers.

baizq