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Script for making data files to plot k-resolved transmission with gnuplot

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M.Albert:
Dear nori
 I can obtain a very beautiful 3D picture with your method,but what physics properties can we analyze from this picture.
 By the way ,how to save the picture  in my computer .I am new to gnuplot ;D
THANK YOU!

Nordland:
I am not a expert at analysis these pictures, but if you calculate the analytic result for the k-space resolved transmission for a tunneling barrier you will get the same picture as Nori shows in his post. Hence getting a k-space resolved transmission spectrum like this, will tell you that your scattering acts as a simple potential barrier.

Saving in gnuplot is a little tricky, but you can write something like:
set terminal png
set output "my_file.png"

And it should save the picture to my_file.png

M.Albert:
Thank you ,I have tried it out.You are right!

nori:
Dear M.Albert,

It might not be easy to take advantage of k-resolved transmission in order to investigate physical(transport) properties in the system,
but in some cases it's useful.

The system "fe/mgo/fe" is a perfect example.
If spin-configuration between electrodes is parallel, k-resolved transmission at fermi-level is like "fe_mgo_fe.png".
In "fe_mgo_fe.png", you can understand following things:
1. The nature of majority transmission is "Tunneling", because maximum value exists at gamma-point and transmission gets monotone decreasing when (kx, ky) gets larger.
(As Nordland mentioned above)
2. The nature of minority transmission is "Resonant Scattering" through interface state(s) between Fe and MgO, because there are some sharp peak away from gamma-point.

In addition, the nature of majority/minority transmission at fermi-level in the case of anti-parallel spin-configuration  is also "Resonant Scattering".
(Please see "femgo_antipara_trans_up.png" offerd by Anders)

These facts are very important for understanding TMR properties in the system "fe/mgo/fe".
For instance, if some adittional layers are inserted between Fe and MgO interface, It is expected that TMR ratio gets better.
Because interface states that contribute to "minority transmission in parallel" and "majority/minority transmission in anti-parallel" are broken by inserting addional layers, the conductances get dramatically decreasing while "majority transmission in parallel" gets little influence.
(Please refer to "Phys. Rev. B 72, 140404 (2005)" for more information)

rosen:
Dear Anders Blom
If i want to plot the curve in an external program other than Pylab, how to pipe the output to a file such as XYZ?

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