Muon spin relaxation study of non-Fermi-liquid behavior near the ferromagnetic quantum critical point in CePd0.15 Rh0.85

The low-energy spin dynamics near the ferromagnetic quantum critical point in CePd0.15 Rh0.85 have been investigated using zero-field (ZF) and longitudinal-field muon spin relaxation (μSR) measurements over a temperature range of 60 mK to 4 K and in applied fields up to 2500 G. The ZF- μSR 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 (λ) exhibits a power-law behavior, λ (T) ∼ T-n with n∼0.8, while the field dependence at 0.1 K reveals a time-field scaling of the muon relaxation function, Pz (t,H) = Pz (t/ Hγ) with γ∼1.0±0.1. Furthermore, the exponent derived from the ZF- μSR data agrees well with the power-law behavior of the temperature-dependent susceptibility, χ (T) ∼ T-α (α∼-0.6±0.1), the E/T scaling of the neutron dynamical susceptibility, as well as the magnetization-field-temperature scaling (γm ∼0.8±0.1), obtained from the same sample. The μSR results of CePd0.15 Rh0.85 are discussed in the context of systems exhibiting non-Fermi-liquid behavior. © 2008 The American Physical Society.