Slow ferromagnetic fluctuations in the kagome metal Sc${}_3$Mn${}_3$Al${}_7$Si${}_5$ revealed by ${}^{27}$Al NMR

Abstract

Static and dynamical magnetic and electronic properties of the kagome metal Sc${}_3$Mn${}_3$Al${}_7$Si${}_5$ have been investigated by ${}^{27}$Al nuclear magnetic resonance (NMR) measurements. The temperature dependence of Knight shift ($K$) shows a similar temperature dependence of the DC magnetic susceptibility $\chi$ except for the low-temperature region below $\sim$ 50 K where $K$ is almost constant while $\chi$ keeps increasing, which suggests that the increase in $\chi$ at low temperatures is not intrinsic. ${}^{27}$Al spin-lattice relaxation rate divided by temperature ($1/T_{1}T$) is found to be constant, confirming the metallic state of Sc${}_3$Mn${}_3$Al${}_7$Si${}_5$ from a microscopic point of view. Based on a Korringa ratio analysis using the $T_1$ and $K$ data, ferromagnetic spin fluctuations are found to dominate in Sc${}_3$Mn${}_3$Al${}_7$Si${}_5$. These fluctuations are suggested to be very slow with frequencies on the order of kilohertz or lower.

6 pages, 4 figures