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Abstracts
Scanning tunneling microscopy images and scanning tunneling spectroscopy characteristics were measured at 4.2 K in liquid helium bath on the cleaved in air a-b surface of Bi_{2}Sr_{2}CaCu_{2}O_{8} (BSCCO-2212). Electronic densities of states and superconductivity parameters Δ and Γ evaluated from dI/dV characteristics depend on tip-sample distance s: with shortening of the distance s superconducting gap structure becomes more distinct, i.e. Δ increases and Γ decreases. We explain this phenomenon as a non-vacuum tunneling, where for longer s tunneling electrons reach only the surface contamination layer on non-metallic BiO top-surface layer, whereas for shorter s tunneling electrons penetrate also deeper lying CuO layers reflecting their superconducting properties. The dependence of Δ on s is evaluated. This result allows to understand better the non-vacuum scanning tunneling microscopy imaging: by adjusting properly the tip-sample distance one can select suitable local density of states contributing dominantly to the scanning tunneling microscopy images taken on BSCCO.
Journal
Year
Volume
Issue
Pages
597-604
Physical description
Dates
published
1997-03
received
1996-08-07
(unknown)
1996-12-16
Contributors
author
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa, Poland
author
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa, Poland
author
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa, Poland
References
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Publication order reference
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YADDA identifier
bwmeta1.element.bwnjournal-article-appv91z311kz