De Haas-van Alphen (dHvA) study of the isostructural compounds YbCoIn₅ and LuCoIn₅

The intermetallic compounds RIn3 and RTIn5 (R = rare earth, T = transition metal) have attracted great interest for their large variety of anomalous ground states. Among these are the well-known heavy-fermion superconductors CeCoIn₅ and CeIrIn₅. We present here a dHvA study of YbCoIn₅ and LuCoIn₅, performed by use of a capacitive torque cantilever technique at temperatures down to 0.4 K in magnetic fields up to 13 T. In addition, one single crystal of LuCoIn₅ has been measured in magnetic field up to 34 T. Besides their angular-dependent Fermi-surface topologies, we have also determined the effective masses of the different bands by following the temperature-dependent amplitude changes of the dHvA oscillations. A large number of different dHvA frequencies has been observed for the main crystallographic directions. In contrast to CeCoIn₅ and CeIrIn₅, the cyclotron effective masses for these compounds are in the range from 0.7 to 2.0 m₀.