Ferromagnetism and giant magnetoresistance in the rare-earth fullerides EuSrC

Ishii, Kenji; Fujiwara, Akihiko*; Suematsu, Hiroyoshi*; Kubozono, Yoshihiro*

Physical Review B, 65(13), p.134431_1 - 134431_6, 2002/03

https://doi.org/10.1103/PhysRevB.65.134431

We have studied crystal structure, magnetism and electric transport properties of a europium fulleride EuC and its Sr-substituted compounds, EuSrC. They have a structure, which is an isostructure of other C ( represents an alkali atom or an alkaline earth atom). Magnetic measurements revealed that magnetic moment is ascribed to the divalent europium atom with = 7/2 spin, and a ferromagnetic transition was observed at = 10 - 14 K. In EuC, we also confirm the ferromagnetic transition by heat capacity measurement. The striking feature in EuSrC is very large negative magnetoresistance at low temperature; the resistivity ratio ( = 9 T)/( = 0 T) reaches almost 10 at 1 K in EuC. Such large magnetoresistance is the manifestation of a strong - interaction between conduction carriers on C and 4 electrons of Eu.