Department of Physics, Graduate School of Science, Kyoto University, Kyoto, Japan.
Phys Rev Lett. 2012 Feb 10;108(6):066403. doi: 10.1103/PhysRevLett.108.066403. Epub 2012 Feb 6.
From detailed angle-resolved NMR and Meissner measurements on a ferromagnetic (FM) superconductor UCoGe (T(Curie)∼2.5 K and T(SC)∼0.6 K), we show that superconductivity in UCoGe is tightly coupled with longitudinal FM spin fluctuations along the c axis. We found that magnetic fields along the c axis (H∥c) strongly suppress the FM fluctuations and that the superconductivity is observed in the limited magnetic-field region where the longitudinal FM spin fluctuations are active. These results, combined with model calculations, strongly suggest that the longitudinal FM spin fluctuations tuned by H∥c induce the unique spin-triplet superconductivity in UCoGe. This is the first clear example that FM fluctuations are intimately related with superconductivity.
从对铁磁 (FM) 超导体 UCoGe（居里温度约为 2.5 K 和超导转变温度约为 0.6 K）的详细角分辨 NMR 和迈斯纳测量中，我们表明 UCoGe 中的超导性与沿 c 轴的纵向 FM 自旋涨落紧密耦合。我们发现，沿 c 轴的磁场（H∥c）强烈抑制 FM 涨落，并且超导性出现在纵向 FM 自旋涨落活跃的有限磁场区域内。这些结果结合模型计算，强烈表明 H∥c 调谐的纵向 FM 自旋涨落诱导了 UCoGe 中独特的自旋三重态超导性。这是第一个清楚的例子，表明 FM 涨落与超导性密切相关。
