LOW-TEMPERATURE THERMODYNAMICS OF INVERSE-SQUARE SPIN MODELS IN ONE-DIMENSION

We present a field-theoretic renormalization group calculation in two loop order for classical O(N)-models with an inverse square interactio n in the vicinity of their lower critical dimensionality one. The magn etic susceptibility at low temperatures is shown to diverge like T-a e xp(b/T) with a = (N-2)/(N-1) and b = 2 pi(2)/(N - 1). From a compariso n with the exactly solvable Haldane-Shastry model we find that the sam e temperature dependence applies also to ferromagnetic quantum spin ch ains.