Observation of magnetic fields due to persistent currents in a ring made of a Y sub(1)Ba sub(2)Cu sub(3)O sub(7- delta ) coated conductor

A ring comprising a coated conductor was fabricated. First, the two ends of a biaxially textured Ni tape were connected by means of the atomic diffusion bonding technique. Then buffer layers and a YBCO film were deposited on the ring. All the films were well textured as confirmed by XRD pole figures. The B-H loops, where B and H are the magnetic field at the centre of the ring and the applied field, respectively, were measured as a function of temperature. The persistent current density (J sub(c)) flowing circularly was estimated from the remanent field of B. In the range of temperatures from 72 to 20 K, J sub(c) changed from 0 to 2x10 super(5) A cm super(-2).