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Thermodynamics Of Integrable Chains With Alternating Spins, H. J. De Vega, Luca Mezincescu, Rafael I. Nepomechie
Thermodynamics Of Integrable Chains With Alternating Spins, H. J. De Vega, Luca Mezincescu, Rafael I. Nepomechie
Physics Articles and Papers
We consider a two-parameter (c¯,c̃) family of quantum integrable isotropic Hamiltonians for a chain of alternating spins of spin s=1/2 and s=1. We determine the thermodynamics for low-temperature T and small external magnetic field H, with T≪H. In the antiferromagnetic (c¯>0,c̃>0) case, the model has two gapless excitations. In particular, for c¯=c̃, the model is conformally invariant and has central charge cvir=2. When one of these parameters is zero, the Bethe ansatz equations admit an infinite number of solutions with lowest energy.