Evolution of transport and low-energy spin fluctuations in YbXCu4(X=AuandPd) with the application of magnetic field

We have investigated evolution of transport and low-energy spin fluctuation properties of heavy Fermi liquid compounds YbAuCu4 and YbPdCu4 with the application of magnetic field. YbAuCu4 is found to be driven from the originally antiferromagnetically (AFM) ordered ground state (TN∼0.8K) to a nonmagnetic Fermi liquid (FL) one through the field-tuned quantum critical point (QCP) at Hcr≃13kOe(TN→0). In the vicinity of Hcr, the electrical resistivity measurement provides evidence for the increase in the inelastic scattering of heavy electrons, and the 63Cu spin-lattice relaxation rate measurement exhibits the occurrence of AFM spin order instability. Whilst, YbPdCu4 transforms from the originally ferromagnetically (FM) ordered ground state (TC∼0.6K) into the nonmagnetic FL state, without any intermediate NFL phenomena. This result indicates that the competition of the field-stabilized FM correlation and field-destabilized AFM correlation plays an important role on the field-driven quantum critical phenomena.