spin-polarized IV curve

[Summer]

Dear sir,
 I am working on a defective system depending on spin-polarized. The band structure shows spin  splitting phenomenon. What's more,  the band gaps of spin up and spin down are different. However, the IV curves of  spin up and spin down are same. I want to know why the currents of spin up and spin down are same.
 Looking forword to your replies!

[Ulrik G. Vej-Hansen]

Please provide scripts and log-files, otherwise it is very difficult to provide an informed answer.

[Summer]

Thank you for your reply.  my  scripts and log-files are in the attachments.

[Summer]

Sorry, the log file is too large. I can only upload a part of the file.

[Anders Blom]

The current is often not dependent on the band gap unless your device is of a BTBT type. So if the up/down bands are just shifted (similar effective masses and general shape) then I guess there is no strong spin polarization for the current to be expected. But it would be a lot easier to help if you show some results, like the band structure plots and I-V curves...