A coated conductor comprises a substrate supporting a ReBCO superconductor adapted to carry current in a superconducting state. The superconductor is characterized in having peaks in critical current (J.sub.c) of at least 0.2 MA/cm.sup.2 in a magnetic field of about 1 Tesla when the field is applied normal to the surface of the superconductor and when the field is applied parallel to the surface of the superconductor, and further characterized in that the superconductor includes horizontal defects and columnar defects in a size and an amount sufficient to result in the said critical current response. The conductor is characterized in that the ratio of the height of the peaks in the J.sub.c is in the range from 3:1 with the ratio of the field perpendicular (0 degrees) to the field parallel (+/90 degrees) to the range from 3:1 with the ratio of the field parallel to the field perpendicular.

An electronic platform comprising a substrate made of a ABO3 crystal (2) and at least one layer of a two-dimensional conducting sheet of carbon atoms (1) of a thickness between one and four atoms, characterized in that the conducting layer(s) is (are) placed on top of a face of the crystal whose orthogonal axis is at an angle up to 35 of the crystal's spontaneous polarization or c-axis. The invention achieves a sheet resistance lower than 1 /square at temperatures higher than 77K.