Spin-charge separation and fractional statistics in the supersymmetric t-J model at finite temperatures

Exact thermodynamics for the one-dimensional supersymmetric t-J model with inverse-square exchange is given in terms of free spinons and holons both of which obey fractional exclusion statistics with mutual statistical parameters. It is shown that spinons and holons span the complete Hilbert space of hard-core fermions, and that they are free for all temperatures. The strong spin-charge separation appears in that the spin susceptibility is independent of the electron density, and that the charge susceptibility is independent of magnetization at low temperatures. Thermal spin excitations of the SU(K,1) generalized model are identified as free parafermions of order K.