Observation of field-induced single-ion magnetic anisotropy in a multiorbital Kondo alloy (Lu,Yb)Rh2Zn20

We demonstrate field-induced single-ion magnetic anisotropy resulting from the multiorbital Kondo effect on the diluted ytterbium alloy $({\mathrm{Lu}}_{1\ensuremath{-}x}{\mathrm{Yb}}_{x}){\mathrm{Rh}}_{2}{\mathrm{Zn}}_{20}$. Single-ion anisotropic metamagnetic behavior is revealed in low-temperature regions where the local Fermi-liquid state is formed. Specific heat, low-field magnetic susceptibility, and resistivity indicate reproduction of the ground-state properties by the $\mathrm{SU}(N=8)$ Kondo model with a relatively large $c\text{\ensuremath{-}}f$ hybridization of ${T}_{\mathrm{K}}=60.9\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. Dynamical susceptibility measurements on ${\mathrm{YbRh}}_{2}{\mathrm{Zn}}_{20}$ support realizing the multiorbital Kondo ground state in $({\mathrm{Lu}}_{1\ensuremath{-}x}{\mathrm{Yb}}_{x}){\mathrm{Rh}}_{2}{\mathrm{Zn}}_{20}$. The single-ion magnetic anisotropy becomes evident above $\ensuremath{\sim}5\phantom{\rule{0.28em}{0ex}}\mathrm{T}$, which is lower than the isotropic Kondo crossover field of 22.7 T, verifying blurred low-lying crystal field states through the multiorbital Kondo effect.