QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: Aadhityan on December 27, 2016, 11:13

Title: TMR Negative percentage
Post by: Aadhityan on December 27, 2016, 11:13

I am getting negative percentage for TMR  by using the sample script in your example section. What this mean? Does my system structure is wrong?

Title: Re: TMR Negative percentage
Post by: Daniele Stradi on December 28, 2016, 08:45

Difficult to say without even seeing the system structure  :)  It would be great if you can attach it.

Title: Re: TMR Negative percentage
Post by: Daniele Stradi on December 28, 2016, 15:32

Did you read the TMR tutorial for Fe-MgO-Fe?

http://docs.quantumwise.com/tutorials/fe_mgo_fe/fe_mgo_fe.html

Do you manage to get the correct TMR for Fe-MgO-Fe as described in the tutorial?

What makes you think that you should get the same for Fe-MgO-Ni?

Title: Re: TMR Negative percentage
Post by: Aadhityan on December 29, 2016, 18:37

Also some other TMR devices also I tried. Some of them giving positive percentage. But some structure gave negative percentage. I also checked optimization of the devices two three times.

Title: Re: TMR Negative percentage
Post by: Anders Blom on December 29, 2016, 23:04

There is nothing inherently wrong with negative TMR, you can find many such results in the literature by a quick Google search. If it's correct or not, depends of course on how accurately the calculation was set up. But if you look at the definition of the TMR, nothing prevents it from being negative.