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arXiv · 0801.2628

Unusual upper critical field of the ferromagnetic superconductor UCoGe

N. T. Huy·D. E. de Nijs·Y. K. Huang·A. de Visser
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Abstract

We report upper critical field $B_{c2}(T)$ measurements on a single-crystalline sample of the ferromagnetic superconductor UCoGe. $B_{c2}(0)$ obtained for fields applied along the orthorhombic axes exceeds the Pauli limit for $B \parallel a,b$ and shows a strong anisotropy $B_{c2}^{a} \simeq B_{c2}^{b} \gg B_{c2} ^{c}$. This provide evidence for an equal spin pairing state and a superconducting gap function of axial symmetry with point nodes along the c axis, which is also the direction of the uniaxial ferromagnetic moment $m_0 = 0.07 μ_{B}$. An unusual curvature or kink is observed in the temperature variation of $B_{c2}$, which possibly indicates UCoGe is a two-band ferromagnetic superconductor.

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N. T. Huy, D. E. de Nijs, Y. K. Huang, A. de Visser. 2008-01-17. Unusual upper critical field of the ferromagnetic superconductor UCoGe. https://doi.org/10.1103/physrevlett.100.077002

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