Microwave study of superconductivity in alkali-metal-doped C{sub 60} films

Journal Article · Wed Mar 11 04:00:00 EST 1992 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja00032a010· OSTI ID:232270

Glarum, S H; Duclos, S J; Haddon, R C ^[1]

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1. AT&T Bell Labs., Murray Hill, NJ (United States)

The authors have studied the doping of films of C{sub 60} and C{sub 70} by low-temperature alkali-metal vaporization. These films develop visible phase boundaries during the doping process. By using Raman, ESR, and microwave loss (superconductivity) spectroscopies to characterize the doped films in situ, the authors have established the compositions which occur under these conditions. The authors report the first preparation of a K{sub 3}C{sub 60} film in which the superconducting transition temperature approaches that of the bulk materials (T{sub c} = 19 K) and the first observation of superconductivity in an Rb{sub 3}C{sub 60} film (T{sub c} = 25 K). With C{sub 60} films, all of the alkali metals studied (A = Na, K, Rb, Cs) eventually form the insulating A{sub 6}C{sub 60} phase after prolonged doping. The A{sub 3}C{sub 60} phase occurs for A = Na, K, and Rb, but only the K and Rb compounds superconduct above 4 K. Large frequency shifts accompanying the superconducting transition indicate macroscopic microwave flux exclusion volumes and set critical field limits. In low magnetic fields, superconductivity is dominated by weak link behavior, resembling that of polycrystalline high-T{sub c} materials. Superconductivity was not observed with alkali-metal-doped C{sub 70} films. 43 refs., 6 figs., 1 tab.

• Sponsoring Organization: USDOE
• OSTI ID: 232270
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 6 Vol. 114; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CESIUM COMPOUNDS
CHEMICAL PREPARATION
DOPED MATERIALS
FILMS
FULLERENES
MICROWAVE RADIATION
POTASSIUM COMPOUNDS
RAMAN SPECTROSCOPY
RUBIDIUM COMPOUNDS
SODIUM COMPOUNDS
STOICHIOMETRY
SUPERCONDUCTIVITY
TRANSITION TEMPERATURE