Electronic correlation effects in LnFe₂Al₁₀ (Ln=Y, Yb)

We report on physical properties of the two new iron aluminides YFe ₂Al₁₀ and YbFe₂Al₁₀. They are members of a broader rare-earth based family of intermetallics in which unusual properties have been the subject of considerable recent interest. We argue that in both the title compounds electronic correlations are causing a non-Fermi-liquid ground state, but with different consequences for the ground state. Neither of the compounds are magnetically ordered above 0.4 K, but in YFe₂Al₁₀ we find evidence from heat capacity, magnetic susceptibility and ²⁷Al-NMR results that point toward a low-temperature ferromagnetic instability which may be driving this compound into ferromagnetic quantum criticality.