Spin and charge fluctuations in the t-J model

Dynamical spin and charge susceptibilities are calculated for the t-J model in the paramagnetic phase. Spin dynamics is scaled with the exchange interaction J and has a diffusive character in the hydrodynamic limit while the high frequency region shows a spin-wave-like excitation character. The charge excitation spectrum has a damped sound-like propagation mode for small wave vectors and a broad high energy peak(similar to t) for large momenta. (C) 1999 Elsevier Science B.V. All rights reserved.