  Electronic correlations control the normal state of bulk high-Tc cuprates.
Strong correlations also suppress the charge transport through cuprate grain
boundaries (GBs). The question then arises if these correlations can produce
magnetic states at cuprate GBs. We analyze the formation of local magnetic
moments at the GB of a correlated two-dimensional electron systems which is
represented by an inhomogeneous Hubbard model. The model Hamiltonian is
diagonalized after the implementation of a mean-field decoupling. The formation
of local magnetic moments is supported by a sufficiently strong variance in the
bond kinetic energies at the GB. Local scattering potentials can assist or
suppress the formation of a magnetic GB state, depending on the details of
their spacial distribution. Grain boundary induced stripes are formed in the
vicinity the GB and decay into the bulk. Moreover, we observe the build-up of
conducting channels which are confined by magnetic clusters. The grain boundary
resistance increases at decreasing temperatures. This low-temperature behavior
is caused by the suppression of current correlations in the state with local
magnetic GB moments. The resistance upturn at low temperatures is in
qualitative agreement with experiments.
