Quantum oscillations study of the Fermi-surface evolution in Yb-substituted CeCoIn$_{5}$

We report results of systematic de Haas-van Alphen (dHvA) studies on Ce$_{1-x}$Yb$_{x}$CoIn$_{5}$ single crystals with varying Yb concentrations $x$. For a low dilution of $x$ = 0.1, the well-documented Fermi surface and the heavy effective masses of CeCoIn$_{5}$ ($x = 0$) remain nearly unchanged. A clear change of the Fermi-surface topology becomes evident for high Yb concentrations of $x = 0.55$, and above. The effective masses are reduced considerably to values between 0.7 and 2.6 free electron masses. Nevertheless, the superconducting transition temperature $T_c$ and upper critical field $H_{\mathrm{c2}}$ are only weakly suppressed with $x$. The angular-resolved dHvA frequencies for YbCoIn$_{5}$ show a good agreement with our density functional theory band-structure calculation with localized 4$f$ electrons and an Yb valence of 2+, which has been used to constructed the Fermi surface.