4. Mean field model for an antiferromagnet: Denote two sets (up and down) of spins as A and B and consider two sublattic

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4 Mean Field Model For An Antiferromagnet Denote Two Sets Up And Down Of Spins As A And B And Consider Two Sublattic 1 (111.44 KiB) Viewed 39 times

4. Mean field model for an antiferromagnet: Denote two sets (up and down) of spins as A and B and consider two sublattices formed by them in an antiferromagnet. When a magnetic field Bo is applied to this system, let the mean field produced by a sublattice with magnetization M be – aM for the same sublattice and — BM for the other sublattice so that the net H-fields on the two sublattices are H A H 0 αΜ - BM A and - Н. B = H 10 - BM aM B B А N Define Néel temperature T, to be the temperature where non zero magnetization is obtained for zero applied field. Susceptibility of antiferromagnet above Ty is given N by С T+0 where gives the paramagnetic susceptibility. Find T, and 0 in terms of 1 N C, a and B.