External Magnetic Field & Electron Spin Interaction

[The Head]

In my lecture notes, there is a slide about an external field interacting with a system of electron spins. In this situation can we assume that B=B_0 ( or in other words that μ_0*M =0)? I would think so, but does a system of electron spins imply that these electrons belong to some matter configuration (are bound), or can they to be treated as unbound electrons?

 

[Simon Bridge]

You will have to consider all that in the context of the lecture course ... there's not enough information.

 

[The Head]

It's a Solid State Physics Course. The slide says that if you know the external field and the ratio of the number of electrons with spin parallel to anti-parallel that we can calculate the temperature when a field interacts with a set of electron spins.

 

[Simon Bridge]

In solid state the electrons are usually bound to some sort of crystal - the solid.
You'll have done band-theory(?) so the electrons are (usually) treated as bound to a well that spans the entire crystal with the effect of unscreened lattice charges added as a perturbation.