Spectrum and Thermodynamics of the one-dimensional supersymmetric t-J model with 1/r21/r^2 exchange and hopping

We derive the spectrum and the thermodynamics of the one-dimensional supersymmetric t-J model with long range hopping and spin exchange using a set of maximal-spin eigenstates. This spectrum confirms the recent conjecture that the asymptotic Bethe-ansatz spectrum is exact. By empirical determining the spinon degeneracies of each state, we are able to explicitly construct the free energy.Comment: 13 pages, Latex, (published in PRB46, 6639 (1992)