🚀 go-pugleaf

In article <BxJFGI.4D5@wsrcc.com> alison@wsrcc.com (Alison Chaiken) writes:

>The $0.05 answer: The fundamental underlying cause of conduction
>electron "itinerant" ferromagnetism is the Pauli exclusion principle.
>In some sense the exclusion principle causes a repulsive force between
>electrons of the same energy and spin.  (This is really an indirect
>manifestation of the Coulomb repulsion between like charges.)  The
>converse of the preceding statement is that if you have a low-density
>electron gas, there is an effective net force aligning the spins.

Hmm, now that we have solid state theorist talking we should ask some
questions.  I don't get this "converse" at all.  Are you saying that the
Pauli exclusion principle alone causes electron spins to tend to line up
in a dilute electron gas?  That seems mighty weird.  Or do the magnetic
moments of the electrons also play a role?

>Thus, a large-lattice-constant metal will have a tendency towards
>ferromagnetism.

What's the lattice constant, and why does this give you a low-density
electron gas?

>This is especially true in a degenerate system
>because the high density of states at the Fermi level means a big
>energetic win for opening up an energy gap.  

Sorry, I don't get this either.

Feel free to answer as tersely or loquaciously as you like... I think
there are a bunch of us out here that are interested but not quite up to speed.