Ames Laboratory, U.S. DOE, Ames, Iowa 50011, USA.
Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
Phys Rev Lett. 2018 Sep 28;121(13):137204. doi: 10.1103/PhysRevLett.121.137204.
Two ordering states, antiferromagnetism and nematicity, have been observed in most iron-based superconductors (SCs). In contrast to those SCs, the newly discovered SC CaK(Fe_{1-x}Ni_{x}){4}As{4} exhibits an antiferromagnetic (AFM) state, called hedgehog spin-vortex crystal (SVC) structure, without nematic order, providing the opportunity for the investigation into the relationship between spin fluctuations and SC without any effects of nematic fluctuations. Our ^{75}As nuclear magnetic resonance studies on CaK(Fe_{1-x}Ni_{x}){4}As{4} (0≤x≤0.049) revealed that CaKFe_{4}As_{4} is located close to a hidden hedgehog SVC AFM quantum-critical point (QCP). The magnetic QCP without nematicity in CaK(Fe_{1-x}Ni_{x}){4}As{4} highlights the close connection of spin fluctuations and superconductivity in iron-based SCs. The advantage of stoichiometric composition also makes CaKFe_{4}As_{4} an ideal platform for further detailed investigation of the relationship between magnetic QCP and superconductivity in iron-based SCs without disorder effects.
两种有序态，反铁磁性和向列相，已在大多数铁基超导体（SCs）中观察到。与那些SCs 不同，新发现的 SC CaK(Fe_{1-x}Ni_{x}){4}As{4} 表现出反铁磁（AFM）态，称为刺猬自旋涡旋晶体（SVC）结构，没有向列序，为研究没有向列涨落影响的自旋涨落和 SC 之间的关系提供了机会。我们对 CaK(Fe_{1-x}Ni_{x}){4}As{4}（0≤x≤0.049）的 ^{75}As 核磁共振研究表明，CaKFe_{4}As_{4} 接近隐藏的刺猬 SVC AFM 量子临界点（QCP）。CaK(Fe_{1-x}Ni_{x}){4}As{4} 中没有向列性的磁性 QCP 突出了铁基SCs 中自旋涨落和超导性之间的紧密联系。化学计量组成的优势也使得 CaKFe_{4}As_{4} 成为进一步详细研究铁基 SCs 中磁性 QCP 和超导性之间关系的理想平台，而不受无序效应的影响。
