在铁基超导体中通过压力同时优化自旋涨落和超导性。

Simultaneous optimization of spin fluctuations and superconductivity under pressure in an iron-based superconductor.

机构信息

Department of Physics, Renmin University of China, Beijing 100872, China.

School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China.

出版信息

Phys Rev Lett. 2013 Sep 6;111(10):107004. doi: 10.1103/PhysRevLett.111.107004. Epub 2013 Sep 4.

DOI:10.1103/PhysRevLett.111.107004

PMID:25166698

Abstract

We present a high-pressure NMR study of the overdoped iron pnictide superconductor NaFe0.94Co0.06As. The low-energy antiferromagnetic spin fluctuations in the normal state, manifest as the Curie-Weiss upturn in the spin-lattice relaxation rate 1/(75)T1T, first increase strongly with pressure but fall again at P>Popt=2.2 GPa. Neither long-ranged magnetic order nor a structural phase transition is encountered up to 2.5 GPa. The superconducting transition temperature Tc shows a pressure dependence identical to the spin fluctuations. Our observations demonstrate that magnetic correlations and superconductivity are optimized simultaneously as a function of the electronic structure, thereby supporting very strongly a magnetic origin of superconductivity.

摘要

我们呈现了高压 NMR 研究过掺杂铁砷化物超导体 NaFe0.94Co0.06As 的结果。正常态下的低能反铁磁自旋涨落表现为自旋晶格弛豫率 1/(75)T1T 的居里-外斯上翘，首先随压力急剧增加，但在 P>Popt=2.2 GPa 时再次下降。在 2.5 GPa 之前，既没有长程磁有序也没有结构相变。超导转变温度 Tc 表现出与自旋涨落相同的压力依赖性。我们的观察结果表明，磁关联和超导性作为电子结构的函数同时得到优化，从而强烈支持超导性的磁起源。