Macroscopic magnetic properties of high Tc epitaxial Y1Ba2Cu3Ox thin films

Abstract

Macroscopic magnetic characterization of epitaxial high Tc thin films on SrTiO3(110) substrates has been performed using SQUID magnetometry. We have probed the two high symmetry axes which lie in the plane and possess zero macroscopic demagnetization factors ([001] and [1-10]). Zero field cooled and Meissner susceptibility at 10° K for H parallel to the c-axis are similar at 20 Oe, begin to diverge at 100 Oe, and are significantly different at 500 Oe. We estimate Hc1 = 450 Oe for this case. Critical current density determined from magnetization loops, Jabc, for H parallel to the c-axis at 10° K is 3-7×1o6 A/cm2 for H = 2 to 5 kOe and Jcc is about a factor of five or less lower for H applied parallel to the [1-10] direction in the plane which indicates much less anisotropy between the basal plane and c-axis critical currents that has been previously reported in the literature. Jabc shows a relaxation effect as a function of time settling to 1-3×106 A/cm2 for the same field range and temperature after 90 minutes. © 1989.