Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
Phys Rev Lett. 2013 Oct 18;111(16):167001. doi: 10.1103/PhysRevLett.111.167001. Epub 2013 Oct 16.
We investigate the effect of antiferromagnetic (AF) quantum criticality on the magnetic penetration depth λ(T) in line-nodal superconductors, including the cuprates, the iron pnictides, and the heavy-fermion superconductors. The critical magnetic fluctuation renormalizes the current vertex and drastically enhances the zero-temperature penetration depth λ(0), which is more remarkable in the iron-pnictide case due to the Fermi-surface topology. Additional temperature (T) dependence of the current renormalization makes the expected T-linear behavior at low temperatures approach T(1.5) asymptotically. These anomalous behaviors are consistent with experimental observations. We stress that λ(T) is a good probe to detect the AF quantum critical point in the superconducting state.
我们研究了反铁磁（AF）量子临界点对线-节超导体内磁穿透深度λ（T）的影响，包括铜酸盐、铁磷化物和重费米子超导体。临界磁涨落会重整化电流顶点，并极大地增强零温穿透深度λ（0），在铁磷化物的情况下由于费米面拓扑结构更为显著。电流重整化的额外温度（T）依赖性使得在低温下预期的 T-线性行为渐近地趋近于 T(1.5)。这些反常行为与实验观测一致。我们强调，λ（T）是探测超导态中反铁磁量子临界点的一个很好的探针。
