Non−Fermi Liquid−Like Behavior in a Heavy Lanthanide Compound YbFe4P12 with Filled Skutterudite Structure Probed by 31P−NMR

概要

論文の詳細を見る
We have carried out 31P−NMR study on a new intermediate−valence compound YbFe4P12 with a filled skutterudite structure which has heavy fermion−like properties below <TEX>${\sim}10$</TEX> K. The Knight shift has a very small value less than 0.05%, and the linewidth exhibits a monotonic increase without exhibiting any singular behavior down to 0.5 K. The nuclear spin–lattice relaxation rate <TEX>$1/T_{1}T$</TEX> below <TEX>${\sim}50$</TEX> K strongly depends on both the temperature <TEX>$T$</TEX> and applied magnetic field <TEX>$H$</TEX> and follows the power−law relation <TEX>$1/T_{1}T=AT^{-\alpha}$</TEX> over one decade. The power <TEX>$\alpha \sim 0.1$</TEX> at 7.0 T increases with decreasing <TEX>$H$</TEX> and takes the maximum value of <TEX>${\simeq}0.7$</TEX> at 0.2 T, which is close to the value 3/4 expected for the non−Fermi liquid (NFL) state associated with antiferromagnetic spin fluctuations. We suggest that YbFe4P12 is an interesting material in which the NFL−like behavior occurs below a rather high temperature of <TEX>${\sim}10$</TEX> K, and a magnetic field of about 0.2 T is sufficient to bring it to its quantum critical point.
2006-06-15