2014/07/10 by K. Ahilan, T. Imai, A. S. Sefat +1 · 1 citation
Physics and Astronomy · #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.90.014520
published as Physical Review B 90, 014520(2014) · Submitted to PRB
arxiv created 2014/07/10 · arxiv updated 2015/06/22
We use NMR techniques to investigate the magnetic properties of BaCo2As2 single crystals, the non-superconducting end member of the Co-substituted iron-pnictide high Tc superconductor Ba(Fe1-xCox)2As2 with x = 1. We present 75As NMR evidence for enhancement of low frequency spin fluctuations below ~ 100 K. This enhancement is accompanied by that of static uniform spin susceptibility at the wave vector q = 0, suggesting that the primary channel of the spin correlations is ferromagnetic rather than antiferromagnetic. Comparison between the NMR Knight shift 75K and bulk susceptibility chi(bulk) data uncovers the presence of two separate components of spin susceptibility with distinct temperature dependences, presumably because multiple electronic bands crossing the Fermi energy play different roles in the electronic properties of BaCo2As2.