Energy gaps in Bi-Sr-Ca-Cu-O and Bi-Sr-Cu-O systems by electron tunneling

Journal Article · Sun Oct 01 00:00:00 EDT 1989 · Physical Review (Section) B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.40.6902· OSTI ID:5375211

Ekino, T; Akimitsu, J ^[1]

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1. Department of Physics, Aoyama-Gakuin University, 6-16-1 Chitosedai, Setagaya, Tokyo 157, Japan (JP)

We report the results of electron tunneling studies of the Bi-Sr-Ca-Cu-O and Bi-Sr-Cu-O systems by using point-contact tunneling. In these studies, we observed two distinctive energy gaps at each Bi-Sr-Ca-Cu-O system, having extremely large values. The larger values of the ratios 2{Delta}/{ital kT}{sub {ital c}} are 10--12 for Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub {ital y}} and 9--11 for Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}Oi{sub {ital y}} and the smaller values are 5.5--6.1 for Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub {ital y}}. These differences can be attributed to the gap anisotropies and the ratios of gaps are 1.7--1.8 for Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub {ital y}} and 1.5--1.8 for Bi{sub 2}Sr{sub 2}Ca{sub 2}C{sub 3}O{sub {ital y}}. The ratio 2{Delta}/{ital kT}{sub {ital c}} in the Ca-absent material Bi{sub 2}Sr{sub 2}CuO{sub {ital y}} was obtained as 5.4--7.4. The gap values are quite reproducible for the bulk, single crystal, and thin films.

• OSTI ID: 5375211
• Journal Information: Physical Review (Section) B: Condensed Matter; (USA), Vol. 40:10; ISSN 0163-1829
• Country of Publication: United States
• Language: English

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