Spirals in the t-J model and structure of the spin-glass state of La2-xSrxCuO4

Starting from the extended t-J model, we derive an effective model that describes the spin dynamics in the insulating phase of La2-xSrxCuO4, x less than or similar to 0.055, at low temperature. Using Monte Carlo simulations, we show that the destruction of Neel order is driven by the single-hole localization length. A phase transition at 2% doping is consistent with the value of the localization length known from the variable range hopping conductivity. The static spin structure factor obtained in our calculations is in perfect agreement with neutron scattering data over the whole range of doping. Thus we demonstrate that the ground state of La2-xSrxCuO4 at 0.02<x<0.055 is not a simple spin glass, it is a disordered spin spiral state. (C) 2008 Elsevier Ltd. All rights reserved.