Superconductivity of Ba doped C60 — susceptibility results and upper critical field

Superconductivity in fullerides

“…The superconducting fullerides may be divided in five classes; 1) A 3 C 60 (A = K, Rb, Cs or some combination of these elements, 2) Na 2 A x C 60 (x ≤ 1) ( A = K, Rb, Cs or a combination of these, 3) A 3−x Ba x C 60 (A=K, Rb, Cs), 4) Ca x C 60 (x ∼ 5) and Ba 6 C 60 (Kortan et al, 1992b) or Ba 4 C 60 (Baenitz et al, 1995) and Sr 6 C 60 (Kortan et al, 1994) and 5) Yb 2.75 C 60 and Sm x C 60 . A summary is given in Table I.…”

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

“…Some non-cubic superconductors have been obtained for Yb 2:75 C 60 (T c ¼ 6 K), 1006 Sm 2:75 C 60 (T c ¼ 8 K), 1007 Ba 4 C 60 (T c ¼ 6:7 K), 1008,1009 and Sr 4 C 60 (T c ¼ 4:4 K). 1009 Eu 6 C 60 with bcc packing undergoes a ferromagnetic transition at 12 K, arising from Eu 2þ cations with S ¼ 7=2 spin, 1010 and shows a giant negative magnetoresistance arising from a significant %-f coupling between the conduction electrons on C 60 and localized 4 f -electrons on Eu (see section 4.7.1).…”

Magic alkali-fullerene compound clusters of extreme thermal stability

“…This class of materials is particularly interesting because alkali atoms act as electron donor, which can induce superconductivity. 8,9 The stability of C 60 Ba 32 was explained by the decoration of all 32 facets of the fullerene molecules with Ba, thus forming a complete geometrical shell. 10 The magic clusters ͑C 60 K 6 ͒ n K + , on the other hand, were associated with the complete filling of the lowest unoccupied t 1u molecular orbitals of C 60 with the 4s 1 valence electrons of K. 11 The enhanced stability of clusters of a particular size is usually inferred from a substantially increased abundance in the mass spectra of cluster beams.…”