Field-tuned Fermi liquid in quantum critical YFe2Al10

Abstract

We present measurements of the magnetization $M$, ac susceptibility ${\ensuremath{\chi}}^{\ensuremath{'}}$, electrical resistivity $\ensuremath{\rho}$, and specific heat $C$ in single crystals of metallic YFe${}_{2}$Al${}_{10}$. The magnetic susceptibility follows a Curie-Weiss temperature dependence for $75\phantom{\rule{0.28em}{0ex}}\text{K}\ensuremath{\le}T\ensuremath{\le}750$ K, with a fluctuating Fe moment of 0.45${\ensuremath{\mu}}_{B}$/Fe, and the ac susceptibility ${\ensuremath{\chi}}^{\ensuremath{'}}$ diverges at lower temperatures ${\ensuremath{\chi}}^{\ensuremath{'}}\ensuremath{\sim}{T}^{\ensuremath{-}1.28\ifmmode\pm\else\textpm\fi{}0.04}$ when the ac field is in the basal plane. The field $B$ and temperature $T$ dependencies of the magnetization $M$ are well described by the scaling expression $M{T}^{\ensuremath{-}\ensuremath{\beta}}$ $=$ $\mathcal{F}$($B$/$T$${}^{\ensuremath{\beta}+\ensuremath{\gamma}}$) for $1.8\phantom{\rule{0.16em}{0ex}}\phantom{\rule{4pt}{0ex}}\text{K}\ensuremath{\le}T\ensuremath{\le}30$ K and for fields larger than 0.1$T$. These results indicate that strong quasi-two-dimensional critical fluctuations are present that can be suppressed by magnetic fields. The magnetic and electronic parts of the specific heat $C$${}_{M}$ show a similar divergence for $0.4\phantom{\rule{0.28em}{0ex}}\text{K}\ensuremath{\le}T\ensuremath{\le}12$ K, where ${C}_{M}/T\ensuremath{\sim}{T}^{\ensuremath{-}0.47\ifmmode\pm\else\textpm\fi{}0.03}$. The divergences in ${\ensuremath{\chi}}^{\ensuremath{'}}$ and ${C}_{M}/T$ indicate that YFe${}_{2}$Al${}_{10}$ is located near a quantum critical point, and no magnetic order is observed above 0.09 K. We argue that our results are inconsistent with quantum impurity or disorder models, suggesting instead that YFe${}_{2}$Al${}_{10}$ is on the verge of bulk magnetic ordering, and that the critical fluctuations that are associated with this quantum critical point lead to the divergencies in ${C}_{M}/T$ and ${\ensuremath{\chi}}^{\ensuremath{'}}$.