Structural and electronic properties of the overexpanded quaternary superconducting fulleride K 0.25 Rb 0.25 Cs 2.5 C 60

H. Esma Okur, Kosmas Prassides

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The structural and magnetic properties of the overexpanded quaternary K 0.25 Rb 0.25 Cs 2.5 C 60 fulleride are investigated. Rietveld analysis of the high-resolution synchrotron X-ray powder diffraction data shows that K 0.25 Rb 0.25 Cs 2.5 C 60 adopts a cubic structure with face-centered (fcc) symmetry. Magnetization measurements at ambient pressure reveal that the material is a superconductor with a transition temperature, T c , of 29.4 K. Temperature dependence of the magnetic susceptibility does not show a simple temperature-independent Pauli susceptibility term – instead, it shows a cusp at a certain temperature implying an insulator-to-metal crossover on cooling. Complementary high-pressure magnetization measurements to a pressure of 10.2 kbar show a non-monotonic response of T c with a dome-shaped scaling with pressure and a maximum value of 32.4 K at 3.9 kbar. The experimental results are consistent with quaternary K 0.25 Rb 0.25 Cs 2.5 C 60 following the established unconventional behavior of overexpanded fullerides. However, our results also unveil well-defined detrimental cation specific effects on the electronic properties associated with the introduction of increased disorder in the tetrahedral interstices of the fcc fulleride structure.

Original languageEnglish
Pages (from-to)44-49
Number of pages6
JournalJournal of Physics and Chemistry of Solids
Volume131
DOIs
Publication statusPublished - 2019 Aug

Keywords

  • Disorder effects
  • Insulator-to-metal transition
  • Strongly correlated systems
  • Superconductivity

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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