Magnetic incommensurability in a doped Mott insulator

In this paper we explore the incommensurate spatial modulation of spin-spin correlations as the intrinsic property of the doped Mott insulator, descri bed by the t-J model. We show that such an incommensurability is a direct m anifestation of the phase-string effect introduced by doped holes in both o ne- and two-dimensional cases. The magnetic incommensurate peaks of dynamic spin susceptibility in momentum space are in agree ment with the neutron-s cattering measurement of cuprate superconductors in both position and dopin g dependence. In particular, this incommensurate structure can naturally re concile the neutron-scattering and NMR experiments of cuprates. [S0163-1829 (99)03017-9].