SPIN TEXTURE OF WEAKLY DOPED CUO2 PLANES

A model of CuO2 planes weakly doped with partially delocalized holes is considered. The effect of such a hole on the background antiferromagnetic spin texture can be represented by a purely magnetic Hamiltonian H = - SIGMA(ijk) (S(i).S(j) x S(k))2, where the summation is over the four triangles of a single plaquette. We show that this model of randomly distributed chiral spin defects leads to an in-plane spin-correlation length approximately described by xi-1(x, T) = xi-1(0, T) + xi-1(x, 0), consistent with neutron-scattering studies on La2-xSrxCuO4. We then suggest why this relation is obeyed when the charge carriers are both localized and completely mobile. Further, we show that this spin texture compares favorably to measured Raman spectra for small x.