Possibility of superconductivity at 65°C in Sr-Ba-Y-Cu-O system

• Published in: Japanese Journal of Applied Physics Vol. 26; no. 8; pp. L1413 - L1415
• Main Authors: IHARA, H, TERADA, N, JO, M, HIRABAYASHI, M, TOKUMOTO, M, KIMURA, Y, MATSUBARA, T, SUGISSE, R
• Format: Journal Article
• Language: English
• Published: Tokyo Japanese journal of applied physics 01.08.1987
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Physics; Properties of type I and type II superconductors; Superconductivity; Transport properties (electric and thermal conductivity, thermoelectric effects, etc.); Mixed oxidation number; Electrical conductivity; Magnetization; Voltage current curve; Perovskite type compound; Transition metal Compounds; Crystal chemistry; X ray; Experimental study; Non stoichiometric composition; X ray diffraction; Oxide ceramics; Inorganic compound; Barium Copper Strontium Yttrium Oxides Mixed; Photoelectron emission; Non linear effect; High temperature superconductor; Superconducting transition
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/jjap.26.l1413

Transition to a zero-resistance state at 65°C (338 K) was observd in a Sr-Ba-Y-Cu-O system for the first time. A nonlinear I-V characteristic curve was observed at that temperature. The resistivity changed from 5×10 -4 Ωcm to below a measurable limit of 1×10 -8 Ωcm between 71 and 65°C. The zero-resistance state reminiscent of superconductivity was continued for ten days at room temperature in air. A magnetization measurement indicated a very small volume fraction of the room temperature superconducting state, if any. X-ray diffractogram showed almost a single phase of oxygen-deficient perovskite with a trace of unidentified phase. Photoemission measurement showed the coexistence of multivalent Cu ions and a relatively low density of state at Fermi level. The superconductivity can be interpreted by the previously proposed d-hole mechanism.