Theory of coexisting transverse-spin freezing and long-ranged antiferromagnetic order in lightly dopedLa2−xSrxCuO4

We provide an explanation of the spin-freezing transition recently observed by Chou et al. [Phys. Rev. Lett. 71, 2323 (1993)] in ${\mathrm{La}}_{2\mathrm{-}\mathit{x}}$ ${\mathrm{Sr}}_{\mathit{x}}$ ${\mathrm{CuO}}_4$ for x≲0.02. We propose that topological excitations of the two-dimensional Heisenberg quantum antiferromagnet having noncoplanar transverse components have a pair-interaction energy that qualitatively and quantitatively agrees with the observed values of spin-freezing temperature as a function of doping.