Spin transport (diffusion and ballistic)

[mendes]

Can anybody explain in a few words these two modes of spin transport and what are the difference between them. Thanks.

[ExcitonPsi]

In general, ballistic transport is when the scattering length (mean free path) of the particles is large compared to the transport distance. So the particles move in a straight line from point A to point B.

If you are looking at transport on a length scale much larger than the scattering length, there will be many scattering events, and the particle motion will be more like a random walk (instead of a straight line). This is diffusion.

[mendes]

In general, ballistic transport is when the scattering length (mean free path) of the particles is large compared to the transport distance. So the particles move in a straight line from point A to point B.

If you are looking at transport on a length scale much larger than the scattering length, there will be many scattering events, and the particle motion will be more like a random walk (instead of a straight line). This is diffusion.


Thanks a lot. Could u please suggest any reference to read. As I googled this question a lot but did not find reference that treats explains this.

[jsgruszynski]

http://en.wikipedia.org/wiki/Ballistic_transport

http://en.wikipedia.org/wiki/Diffusion

http://en.wikipedia.org/wiki/Mean_free_path

Related ballistic/diffusive transition at Mean Free Path in fluid mechanics is

http://en.wikipedia.org/wiki/Knudsen_number

Googling "Spin Transport" and starting on page 11:

http://www.mpipks-dresden.mpg.de/~cord/dresden.pdf

How hard did you look? All these links were on the 1st page of results of Googling "Ballistic Transport", "Diffusive Transport", "Mean Free Path" and "Spin Transport".