SPINONS, SOLITONS, AND MAGNONS IN ONE-DIMENSIONAL HEISENBERG-ISING ANTIFERROMAGNETS

We calculate the excitation spectra for the 1D Heisenberg-Ising antife rromagnets by expansions around the Ising limit. For S = 1/2, the calc ulated expansion coefficients for the spinon spectra agree term by ter m with the solution of Johnson and McCoy. For S = 1, the solitons beco me gapless before the Heisenberg limit is reached, signaling a transit ion to the Haldane phase. By applying a staggered field we calculate t he one-magnon spectra for the S = 1 Heisenberg chain. For S = 3/2 the quantum renormalization of the spin-wave spectra is calculated to be a pproximately 1.16.