Coexistence of Superconductivity and Itinerant Ferromagnetism;
Y₉Co₇ as an Example

A. Kołodziejczyk
Department of Solid State Physics,
AGH University of Science and Technology,
30-059 Cracow, Poland;
e-mail: [email protected]

Abstract - The discovery of superconductivity in Y₉Co₇ that exhibited at the same time the itinerant ferromagnetism was a big surprise because it showed that the two incompatible phenomena might be reconciled at some temperatures under certain thermodynamic conditions. It was 27 years ago. The recently discovered itinerant ferromagnetic superconductors are those strongly correlated electron compounds: UGe₂, UGeRh and likely also ZrZn₂. This review is concentrated on the present thinking about and activities on the problem of coexistence of itinerant ferromagnetism and superconductivity with special emphasis on the first weak itinerant spin- fluctuating ferromagnetic superconductor Y₉Co₇.

Manuscript  received June 15, 2007; final version accepted June 27,2007; Reference No. CR1; Category 1.