Pinning of vortices and critical current in the presence of parallel twinning planes

Magnetic and transport properties of superconductors with a periodic array of twinning planes (TP's) are studied for the case of an increase of the critical temperature in the neighborhood of a TP. Based on the modified London model, the critical magnetic field H_c1, the barrier field H_s, and the critical current j_c(H) are calculated for low temperatures much less than T_c. For resonant vortex configurations, a peak in the curve j_c(H) is predicted with a peak value which cannot be larger than 10⁶ A/cm². Furthermore, the interplay of the bulk and surface pinning for TT_c as well as the magnetic and transport properties for T_c0c are studied.On leave from the Institute of Physics, Belgrade University, Belgrade, Yugoslavia. Also affiliated with Fachbereich Physik WE 5, Freie Universität Berlin, D-1000 Berlin 33.