Field sweep rate effect on the flux creep in HTSC

We report the effect of the magnetic field sweep rare on the relaxation of the magnetization as a function of temperature and magnetic field H paralle l to the c-axis in an aligned powder, thin him and melt textured YBaCuO sup erconductors. The real M vs. lnt relationship can be deduced from the exper imental one by scaling the time t to t+tau +t(0). The resulting curves coll apse all into a single one. The correlation time tau is calculated and it o beys to the relation (dH/dt)(-1) for small T and H. The behavior of the M(l nt) curves cannot be described by the Kim-Anderson model for all the explor ed temperatures and fields.