Magnetization studies of near-room-temperature flux-trapping phenomenon in CuO-based materials

Abstract

DC magnetization studies on a variety of ceramic and crystalline YBaCuO samples indicate a superconducting-like flux-trappinig behavior occurring at similar temperatures as zero-resistance transition temperatures observed near room temperature. The flux-trapping behavior is exemplified by diamagnetic-like deviations from a positive magnetic background in the zero-field-cooled magnetization, by a divergence between the zero-field-cooled and field-cooled magnetization data, or by a positive Meissner effect in the field-cooled magnetization. These behaviors are consistent with a high-Tc (>250 K) superconducting phase in an inhomogeneous superconductor where the superconducting regions exist as defect structures or surface coatings and whose volume fraction is less than a few percent.