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Phys. Rev. B 59, 4439–4444 (1999)

Pressure dependence of superconductivity in the Na2Rb0.5Cs0.5C60 fulleride

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Craig M. Brown
School of Chemistry, Physics and Environmental Science, University of Sussex, Brighton, BN1 9QJ, United Kingdom
Institute Laue Langevin, F-38042 Grenoble, France

Taishi Takenobu
Japan Advanced Institute of Science and Technology, Tatsunokuchi, Ishikawa 923-1292, Japan

Konstantinos Kordatos and Kosmas Prassides
School of Chemistry, Physics and Environmental Science, University of Sussex, Brighton, BN1 9QJ, United Kingdom

Yoshihiro Iwasa
Japan Advanced Institute of Science and Technology, Tatsunokuchi, Ishikawa 923-1292, Japan

Katsumi Tanigaki
Department of Materials Science, Faculty of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan

Received 23 July 1998; published in the issue dated 1 February 1999

The pressure dependence of the superconducting transition temperature Tc of the primitive cubic quaternary fulleride Na2Rb0.5Cs0.5C60 (Tc=8.4K at ambient pressure) is studied by the ac susceptibility technique to 2.5 kbar. The observed value of dTc/dP is -1.22(2) K/kbar. Using the compressibility data available for Na2CsC60, we find that the evolution of Tc with interfullerene spacing in Na2Rb0.5Cs0.5C60 mimics that observed for Na2CsC60 and is comparable to the fcc fulleride K3C60. However, the rate of change, dTc/da, is about 5–6 times smaller than that reported for the quaternary fullerides Na2Rb1-xCsxC60 as a function of x at ambient pressure, implying the presence of a strong alkali-metal specific effect, responsible for the differing effects of chemical and physical pressure on the superconducting properties of Pa3¯ fullerides.

© 1999 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.59.4439
DOI:
10.1103/PhysRevB.59.4439
PACS:
74.70.Wz