TRANSPORT AND CHARGE MAGNETIC ORDER IN THE 2D HOLSTEIN T-T'-J MODEL/

The magnetic phase diagram of the t-t'-J model is presented, where in the framework of a spin-rotation-invariant slave-boson approach incomm ensurate magnetic structures are taken into account. Including Gaussia n fluctuations, a general expression for the dynamic spin and charge s usceptibilities of the t-t'-J model is derived, which goes beyond RPA. The doping dependence of the Hall resistivity is calculated, the resu lts being in accord with experiments on LSCO and YBCO. The commensurat e charge/lattice modulations, reported recently for the isostructural nickelates at quarter filling, can be understood in terms of the 2D Ho lstein-t-J model.