Non-Fermi liquid behavior with and without quantum criticality in Ce$_{\mathrm{1-x}}$Yb$_{\mathrm{x}}$CoIn$_5$

In a growing number of f-electron systems the non-Fermi liquid (NFL) behavior occurs in the absence of an obvious quantum phase transition (QPT), which takes place at a quantum critical point (QCP). An intriguing candidate is Ce$_{\mathrm{1-x}}$Yb$_{\mathrm{x}}$CoIn$_5$ that exhibits an unconventional T -- x phase diagram without an apparent QCP. Therefore, it is important to elucidate the nature of the NFL behavior and to search for possible QCPs in this system Here we reveal a field induced QCP (H$_{\mathrm{QCP}})$ through normal state magneto-resistivity measurements and find its evolution with x. The full suppression of H$_{\mathrm{QCP}}$ for x \textgreater\ 0.2 has surprisingly little effect on the Kondo lattice coherence. At low Yb concentrations, resistivity consists of two contributions with linear and sub-linear temperature dependences, while at higher concentrations only the sub-linear term is present. These results imply that the NFL behavior could be a new state of matter in its own right rather than a consequence of the underlying QPT.