Tuning the Kondo effect in YbFe$_{1-x}$Co$_{x}$Zn$_{20}$

YbCo$_{2}$Zn$_{20}$ is a heavy fermion compound with a Sommerfeld coefficient, $\gamma$ value, of about 8000 mJ/mol-K$^{2}$ with an estimated single ion Kondo temperature, T$_{K}$, of about 1.5 K. One the other hand, YbFe$_{2}$Zn$_{20}$ is less heavy with $\gamma \sim$ 500 mJ/mol-K$^{2}$ and T$_{K} \sim$ 30 K. From a generalized Kadowaki-Woods picture, degeneracies that relate to their Kondo phenomena are large while different: 8 for YbFe$_{2}$Zn$_{20}$ and 4 for YbCo$_{2}$Zn$_{20}$ [1]. In order to understand the effects of Fe-Co substitution on the Kondo effect, a family of YbFe$_{1-x}$Co$_{x}$Zn$_{20}$ were studied. We performed zero-field resistivity and specific heat measurements on single crystals of YbFe$_{1-x}$Co$_{x}$Zn$_{20}$ that were synthesized using a high-temperature solution growth technique [2]. The Kondo characteristic temperatures do not change monotonically in between pure YbFe$_{2}$Zn$_{20}$ and YbCo$_{2}$Zn$_{20}$. Data and a summarize phase diagram of characteristic temperatures as a function of Co doping will be presented and discussed. \\[4pt] [1] M. S. Torikachvili et al. Proc. Natl. Acad. Sci. USA 104, 9960 (2007) \\[0pt] [2] S. Jia et al. Nat. Phys. 3, 334 (2007)