Muon spin relaxation study of non-Fermi-liquid behavior near the ferromagnetic quantum critical point inCePd0.15Rh0.85

Abstract

The low-energy spin dynamics near the ferromagnetic quantum critical point in ${\text{CePd}}_{0.15}{\text{Rh}}_{0.85}$ have been investigated using zero-field (ZF) and longitudinal-field muon spin relaxation $(\ensuremath{\mu}\text{SR})$ measurements over a temperature range of 60 mK to 4 K and in applied fields up to 2500 G. The ZF-$\ensuremath{\mu}\text{SR}$ measurements reveal a considerable slowing down of the spin fluctuations with decreasing temperatures below 2 K. There is no clear sign of either static long-range magnetic ordering or spin freezing down to 60 mK. The temperature dependence of the ZF-muon depolarization rate $(\ensuremath{\lambda})$ exhibits a power-law behavior, $\ensuremath{\lambda}(T)\ensuremath{\sim}{T}^{\ensuremath{-}n}$ with $n\ensuremath{\sim}0.8$, while the field dependence at 0.1 K reveals a time-field scaling of the muon relaxation function, ${P}_{z}(t,H)={P}_{z}(t/{H}^{\ensuremath{\gamma}})$ with $\ensuremath{\gamma}\ensuremath{\sim}1.0\ifmmode\pm\else\textpm\fi{}0.1$. Furthermore, the exponent derived from the ZF-$\ensuremath{\mu}\text{SR}$ data agrees well with the power-law behavior of the temperature-dependent susceptibility, $\ensuremath{\chi}(T)\ensuremath{\sim}{T}^{\ensuremath{-}\ensuremath{\alpha}}$ $(\ensuremath{\alpha}\ensuremath{\sim}\ensuremath{-}0.6\ifmmode\pm\else\textpm\fi{}0.1)$, the $E/T$ scaling of the neutron dynamical susceptibility, as well as the magnetization-field-temperature scaling $({\ensuremath{\gamma}}_{m}\ensuremath{\sim}0.8\ifmmode\pm\else\textpm\fi{}0.1)$, obtained from the same sample. The $\ensuremath{\mu}\text{SR}$ results of ${\text{CePd}}_{0.15}{\text{Rh}}_{0.85}$ are discussed in the context of systems exhibiting non-Fermi-liquid behavior.