Theory of anisotropic hopping transport due to spiral correlations in the spin-glass phase of underdoped cuprate superconductors

We study the in-plane resistivity anisotropy in the spin-glass phase of the high-T-c cuprates, on the basis of holes moving in a spiral spin background. This picture follows from analysis of the extended t-J model with Coulomb impurities. In the variable-range hopping regime the resistivity anisotropy is found to have a maximum value of around 90%, and it decreases with temperature, in excellent agreement with experiments in La2-xSrxCuO4. In our approach the transport anisotropy is due to the noncollinearity of the spiral spin state, rather than an intrinsic tendency of the charges to self-organize.