Remanent magnetization in single crystals of YBa₂Cu ₃O₇

Measurements of the isothermal remanent magnetization M_r and the dc demagnetization remanence M_d have been made on single crystals of YBa₂Cu₃O₇ with the applied magnetic field parallel to the c axis. Plots of M_d vs M_r indicate the presence of interactions when the usual interpretation developed for ferromagnetic systems is applied. However, this interpretation neglects the intrinsic response of a superconductor to expel the flux with supercurrents. It is found that the plots, although suggesting repulsive interactions, are qualitatively explained by the Bean critical state model. In addition the use of the M_d vs M_r plots in connection with the Bean model provides an alternative technique to determine critical currents.