FLUX-PINNING IN HGBA2CUO4+X SINGLE-CRYSTALS

Magnetization studies on single crystals of HgBa2CuO4+x, with T-c onse t approximate to 81 K, were performed in a wide range of temperature a nd magnetic field. The fishtail shape of M(H) loop was observed even a t 5 K. The irreversibility field and the peak position are well descri bed by the power law dependence H-irr/peak(T) = H-irr/peak(0)(1 - T/T- c)(alpha) with the same exponent alpha = 1.8+/-0.1. The pinning force in the fishtail region scales with reduced magnetic field H/H-irr, in the wide temperature range. The normalized pinning force is well descr ibed by the relation: F-p/F-p(max) = A.h(29).(1 - h)(3.8), where h = H /H-irr and A is a numerical parameter.