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A solvable quantum antiferromagnet model
We introduce a quantum antiferromagnet model, having exactly soluble
thermodynamic properties. It is an infinite range antiferromagnetic Ising model
put in a transverse field. The free energy gives the ground state energy in the
zero temperature limit and it also gives the low temperature behaviour of the
specific heat, the exponential variation of which gives the precise gap
magnitude in the excitation spectrum of the system. The detailed behaviour of
the (random sublattice) staggard magnetisation and susceptibilities are
obtained and studied near the N\'eel temperature and the zero temperature
quantum critical point.Comment: 4 pages, 2 eps figure
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