We have performed ^{ 31}P-NMR measurements on Ce(Ru_{ 1-x}Fe_{ x})PO in order to investigate ferromagnetic (FM) quantum criticality, since heavy-fermion (HF) ferromagnet CeRuPO with a two-dimensional structure turns to a HF paramagnet by an isovalent Fe-substitution for Ru. We found that Ce(Ru_{ 0.15}Fe_{ 0.85})PO shows critical fluctuations down to \sim 0.3 K, as well as the continuous suppression of Curie temperature and the ordered moments by the Fe-substitution. These experimental results suggest the presence of a FM quantum critical point (QCP) at x \sim 0.86, which is a rare example among itinerant ferromagnets. In addition, we point out that the critical behaviors in Ce(Ru_{ 0.15}Fe_{ 0.85})PO share the similarity with those in YbRh_{ 2}Si_{ 2}, where the local criticality of $f$ electrons has been discussed. We reveal that Ce(Ru_{ 1-x}Fe_{ x})PO is a new system to study FM quantum criticality in HF compounds.
Categories: cond-mat.str-el cond-mat.mtrl-sci cond-mat.supr-con