Messages

1

General Questions and Answers / Re: magnetic tunnel junction

« on: April 10, 2012, 12:05 »

Hello to all


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


Thanks in advance for support 

2

General Questions and Answers / Re: magnetic tunnel junction

« on: April 6, 2012, 07:15 »

Thanks for your response 

3

General Questions and Answers / Band structure of MTJ

« on: March 29, 2012, 14:42 »

hiiiiii 
i am trying to find out del1,del2 etc band for Co/MgO/Co at K||=0 along (0,0,1) direction for both majority and minority spin. but i am not well good in programming 
so please send me a simple script for finding it out
i will be thankful for it 

4

General Questions and Answers / Re: magnetic tunnel junction

« on: March 29, 2012, 11:42 »

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

5

General Questions and Answers / Re: magnetic tunnel junction

« on: March 27, 2012, 07:47 »

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  

6

General Questions and Answers / Re: magnetic tunnel junction

« on: March 25, 2012, 10:35 »

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)??

7

General Questions and Answers / Re: magnetic tunnel junction

« on: March 19, 2012, 08:46 »

hiiii
thanks for your reply 
sir i have found the k parallel transmission curve but i want to analyze it in 3D for better appearance...
but i am not good in programming at python 
so please may you send me a simple script of analysing it in 3D....
i am also attaching my 2D graph with this.... 

reply please

8

General Questions and Answers / parameter for MTJ

« on: March 14, 2012, 07:16 »

hii..
please anyone tell me the best Poisson solver for magnetic tunnel junction..... (FFT/FFT2D/multi-grid)

9

General Questions and Answers / Re: magnetic tunnel junction

« on: March 1, 2012, 10:32 »

how can i apply the magnetic field on MTJ of different value? and often sometime i tried to find out the change in TMR by changing the insulator length? but manually it takes a long time because i have to optimize my structure first for accurate result, after that i work on device configuration. is their any other method of doing this???  

10

General Questions and Answers / Re: magnetic tunnel junction

« on: February 29, 2012, 10:05 »

please tell me anyone which type of error is this?

Traceback (most recent call last):
  File "c:\users\user2\appdata\local\temp\6727543481552833.py", line 248, in <module>
    nlsave('D:/paper fig/cofeb_anti28feb12k.nc', transmission_spectrum)
  File ".\zipdir\NL\IO\NLSaveUtilities.py", line 154, in nlsave
  File ".\zipdir\NL\IO\IOUtilityFunctions.py", line 543, in createNetCDFFile
  File ".\build\atkpython\lib\shutil.py", line 88, in copy
  File ".\build\atkpython\lib\shutil.py", line 54, in copyfile
  File ".\build\atkpython\lib\shutil.py", line 30, in copyfileobj
IOError: [Errno 28] No space left on device
 
this comes when i tried to perform "anti parallel spin" case. and due to this my k parallel graph got affect. how could i ignore that

11

General Questions and Answers / Re: magnetic tunnel junction

« on: February 3, 2012, 07:45 »

sir is it necessary to optimize same structure again when i worked for different temperature???
  

12

General Questions and Answers / Re: magnetic tunnel junction

« on: January 13, 2012, 12:45 »

means i have to run the TMR calculation by changing the length of electrode or insulator manually.. ok

sir i have one more question

I have studied your tutorial regarding Fe-Mgo-Fe. In chapter 4 of that tutorial you make your spin "-1" for 14 to 23 atom(from second last insulating layer when moving left to right)for anti-parallel case. but i calculated my total energy calculation form 12-23 and 14-23 with "-1" spin. This both of calculation gives same "total energy" result. then how u decide that the  "-1" spin will be only from 14-23.  

and in another question  i have calculate the density of state for cofe/mgo/cofe foe parallel case(all atom have "+1" spin). this graph i am attaching. please tell me is it correct or not? because characteristic of this curve is some like strange.

Thanks 

13

General Questions and Answers / Re: magnetic tunnel junction

« on: January 9, 2012, 10:45 »

thank you for your reply sir....

I have optimized my image, and after optimization the electrode length was automatically set.  now i am working on device configuration. Here i want to plot the graph between the conductance ratio(parallel conductance/ anti parallel conductance) to "per layer thickness of cofeb"

but how can i draw this graph? 


 

14

General Questions and Answers / magnetic tunnel junction

« on: January 6, 2012, 06:53 »

Hiiii i am new to atk vnl.. i am working on the cofeb/mgo/cofeb magneto tunnel junction for this purpose i made the structure using replacing the fe atom with co and at the interface with mgo i attach single boron atom but due to this the bond between the boron and other atom(fe or co) was borken hence i reduce the distance (2.177A) as shown in fig 1.
then i optimize the bulk structure with forces and stress .05. which takes a long time. i select my k point 6,6,3 for this optimization. and for better convergence i kept electron temp 1200K.
but i have following doubt  
1> is it a correct structure?
2> i am facing the problem with convergence in the optimization process as below...
# Warning: The calculation did not converge to the requested tolerance!        #

how could i handle this..
3> now after optimization and during the parallel and anti-parallel confg how may i decide the electrode length in device configuration?

4> and at last how to study about Mulliken population and k-parallel and antiparallel transmission curve for majority and minority spin..

5>How can i make my calculation faster with rough result?
please tell me any one.....