Weak itinerant ferromagnetism and clean superconductivity in Y₉Co₇

Abstract

We present low-temperature magnetic properties for a high-quality polycrystalline sample of the first ferromagnetic superconductor Y₉Co₇. The results of susceptibility and magnetization measurements show the coexistence of a weak itinerant ferromagnetic order with a Curie temperature of T_C ≅ 4.5 K and superconductivity below T_S = 3 K. Several electronic quantities and parameters characterizing the superconducting and normal state are calculated within the Ginzburg–Landau–Abrikosov–Gorkov theory. The data reveal clean limit superconductivity in Y₉Co₇ due to the good chemical purity and structural order of the specimen.

Keywords:

• Y₉Co₇
• coexistence of weak ferromagnetism and clean superconductivity
• resistivity
• magnetic susceptibility
• magnetisation
• specific heat

PACS numbers:

• 74.70Ad
• 74.20.De
• 74.25.fc
• 74.62.Bf

Additional information

Funding

This work was financially supported by the Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Cracow, the Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, and from the Ministry of Science and Higher Education, Poland.