High-Field de Haas-van Alphen Effect in non-centrosymmetric CeCoGe3 and LaCoGe3

We report on de Haas-van Alphen effect measurements in the non-centrosymmetric systems CeCoGe3 and LaCoGe3 in magnetic field up to 28 Tesla. In both compounds, two new high frequencies were observed in high fields. The frequencies were not detected in previous lower field measurements. The frequencies do not originate from magnetic breakdown, and, therefore, are likely to be intrinsic features of the compounds. In CeCoGe3, the corresponding effective masses are strongly enhanced, being of the order of 30 bare electron masses.