Ames Laboratory, U.S. Department of Energy and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Phys Rev Lett. 2013 Nov 27;111(22):227002. doi: 10.1103/PhysRevLett.111.227002.
The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the nonsuperconducting collapsed tetragonal phase of CaFe2As2 via inelastic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetragonal phase of CaFe2As2 is nonmagnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds.
反铁磁自旋涨落与超导性之间的关系已成为铁磷化物超导研究的核心课题。我们通过非弹性中子散射飞行时间数据提供了确凿证据，表明在非超导的 CaFe2As2 坍塌四方相中不存在磁涨落，这与自旋涨落是铁磷化物中非常规超导的必要组成部分的观点一致。我们证明了 CaFe2As2 的坍塌四方相是无磁性的，并根据最近有关密切相关化合物的坍塌四方相高温超导的报道讨论了这一结果。
