${}^{75}\mathrm{As}$ nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements have been carried out to investigate the magnetic and electronic properties of the filled skutterudite metallic compound ${\mathrm{SrFe}}_4{\mathrm{As}}_{12}$. The temperature dependence of Knight shift $K$ determined by the NQR spectrum under a small magnetic field $\left(\le 0.5\mathrm{T}\right)$ shows the similar temperature dependence of the magnetic susceptibility $\chi$ which exhibits a broad maximum at $T^{*}\sim 50$ K. The nuclear spin-lattice relaxation rate divided by temperature $1/T_{1}T$ increases with decreasing temperature and exhibits a broad maximum at $T\sim 70$ K, similar to the case of $\chi$. The temperature dependence of $K$ and $1/T_{1}T$ is reasonably explained by a simple model where we assume a concave-shaped band structure near the Fermi energy. Based on a Korringa ratio analysis using the $T_1$ and $K$ data, ferromagnetic spin fluctuations are found to exist in ${\mathrm{SrFe}}_4{\mathrm{As}}_{12}$. These results indicate that ${\mathrm{SrFe}}_4{\mathrm{As}}_{12}$ can be characterized to be a metal with ferromagnetic correlations and also the peculiar band structure responsible for the suppression of $1/T_{1}T$ and $K$ at low temperatures.

• Received 18 August 2018
• Revised 9 October 2018

DOI:https://doi.org/10.1103/PhysRevB.98.155149