Quantum criticality in single crystalline YFe2Al10 determined from zero-field and longitudinal-field muon spin relaxation*

Muon spin relaxation ($\mu$SR) measurements were performed on single crystalline YFe$_2$Al$_{10}$ down to 19 mK and in magnetic fields up to $\sim$100 Oe. Zero-field-$\mu$SR measurements showed no evidence of magnetic order down to 19 mK, consistent with previous measurements. However, we also find that the depolarization rate $\Lambda$ is temperature independent above 1 K but increases in an exponential behavior for $T <$ 1 K. Longitudinal-field $\mu$SR measurements also reveals a time-field scaling where $G(t, H)$ = $G(t/H^{\gamma}$), with $\gamma$ = 0.67. This is further confirmed from the magnetic field dependence of $\Lambda$, which finds $\Lambda(H) \propto H^{0.67}$ at 19 mK. This is further evidence that single crystalline YFe$_2$Al$_{10}$ is in close proximity to a ferromagnetic quantum critical point.