Solid State Physics 2014
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Revision question 6.13
Posted by MRH on May 3, 2014, 3:58 pm
Using mean field theory, I found (no modulus) = - tanh ( gubbins *) |
This gives =0 at every site always. This is consistent with the fact that Cu and Zn are in equal nos (though I am not sure that I have assumed that).
However the sheet asks us to find
< mod(sigma)> = tanh (gubbins *
Given that sigma always equals -1 or 1 at every site, mod(sigma) will always equal 1, so this solution must be incorrect.
Moreover, if my equation read (no modulus) = tanh ( gubbins *)
I should be very worried, since this would imply that at some temperature I could have at a site non-zero. All sites would have the same . This would imply that we no longer had equal nos of Zn and Cu, which is disallowed (though, I am not sure how the assumption was used, if at all).
What is going on?
- Revision question 6.13 - MRH May 3, 2014, 3:58 pm
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