Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Phys Rev Lett. 2010 Sep 3;105(10):107003. doi: 10.1103/PhysRevLett.105.107003. Epub 2010 Sep 2.
Spin dynamics evolution of BaFe2(As(1-x)Px){2} was probed as a function of P concentration via 31P NMR. Our NMR study reveals that two-dimensional antiferromagnetic (AF) fluctuations are notably enhanced with little change in static susceptibility on approaching the AF phase from the superconducting dome. Moreover, the magnetically ordered temperature θ deduced from the relaxation rate vanishes at optimal doping. These results provide clear-cut evidence for a quantum-critical point, suggesting that the AF fluctuations associated with the quantum-critical point play a central role in the high-T(c) superconductivity.
通过 31P NMR 研究了 BaFe2(As(1-x)Px){2} 的自旋动力学演化随 P 浓度的变化。我们的 NMR 研究表明，在从超导圆顶接近反铁磁（AF）相时，二维 AF 涨落明显增强，静态磁化率几乎没有变化。此外，从弛豫率推断出的有序温度θ在最佳掺杂时消失。这些结果为量子临界点提供了明确的证据，表明与量子临界点相关的 AF 涨落在高温超导中起着核心作用。
