Superconductivity on the border of weak itinerant ferromagnetism in UCoGe.
We report the coexistence of ferromagnetic order and superconductivity in UCoGe at ambient pressure. Magnetization measurements show that UCoGe is a weak ferromagnet with a Curie temperature T(C)=3 K and a small ordered moment m(0)=0.03 micro(B). Superconductivity is observed with a resistive transition temperature T(s)=0.8 K for the best sample. Thermal-expansion and specific-heat measurements provide solid evidence for bulk magnetism and superconductivity. The proximity to a ferromagnetic instability, the defect sensitivity of T(s), and the absence of Pauli limiting, suggest triplet superconductivity mediated by critical ferromagnetic fluctuations.
Huy
N T
NT
Van der Waals-Zeeman Institute, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam, The Netherlands.
Gasparini
A
A
de Nijs
D E
DE
Huang
Y
Y
Klaasse
J C P
JC
Gortenmulder
T
T
de Visser
A
A
Hamann
A
A
Görlach
T
T
Löhneysen
H V
HV