Evolution of transport and low-energy spin fluctuations in ${\mathrm{YbXCu}}_4(\mathrm{X}=\mathrm{Au}\mathrm{and}\mathrm{Pd})$ with the application of magnetic field

Abstract

We have investigated evolution of transport and low-energy spin fluctuation properties of heavy Fermi liquid compounds ${\mathrm{YbAuCu}}_4$ and ${\mathrm{YbPdCu}}_4$ with the application of magnetic field. ${\mathrm{YbAuCu}}_4$ is found to be driven from the originally antiferromagnetically (AFM) ordered ground state ($T_{\mathrm{N}}\sim 0.8\mathrm{K}$) to a nonmagnetic Fermi liquid (FL) one through the field-tuned quantum critical point (QCP) at $H_{\mathrm{cr}}\simeq 13\mathrm{kOe}(T_{\mathrm{N}}\to 0)$. In the vicinity of $H_{\mathrm{cr}}$, the electrical resistivity measurement provides evidence for the increase in the inelastic scattering of heavy electrons, and the ${}^{63}\mathrm{Cu}$ spin-lattice relaxation rate measurement exhibits the occurrence of AFM spin order instability. Whilst, ${\mathrm{YbPdCu}}_4$ transforms from the originally ferromagnetically (FM) ordered ground state ($T_{\mathrm{C}}\sim 0.6\mathrm{K}$) 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.