NIST Center for Neutron Research, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA.
Phys Rev Lett. 2011 Oct 28;107(18):187202. doi: 10.1103/PhysRevLett.107.187202. Epub 2011 Oct 27.
We report neutron scattering measurements of critical magnetic excitations in the weakly ferromagnetic superconductor UCoGe. The strong non-Landau damping of the excitations we observe, although unusual, has been found in another related ferromagnet, UGe(2) at zero pressure. However, we also find that there is a significant anisotropy of the magnetic correlation length in UCoGe that contrasts with an almost isotropic length for UGe(2). The values of the magnetic correlation length and damping are found to be compatible with superconductivity on small Fermi-surface pockets. The anisotropy may be important to explain why UCoGe is a superconductor at zero pressure while UGe(2) is not.
我们报告了在弱铁磁超导体 UCoGe 中临界磁激发的中子散射测量结果。我们观察到的激发的强非 Landau 阻尼虽然不寻常，但在另一个相关的零压铁磁体 UGe(2)中也有发现。然而，我们还发现 UCoGe 中的磁关联长度存在显著各向异性，这与 UGe(2)的几乎各向同性长度形成对比。磁关联长度和阻尼的值与小费米面口袋中的超导性兼容。这种各向异性对于解释为什么 UCoGe 在零压下是超导体而 UGe(2) 不是可能很重要。
