Many-body effects in LuNi₂B₂C

We present de Haas–van Alphen measurements of the nonmagnetic borocarbide superconductor LuNi₂B₂C. The electronic band structure is extracted from the magnetic quantum oscillations in the normal state. In accordance with previous investigations we find a complex band structure with different open and closed Fermi-surface sheets. From the temperature dependence of the oscillations amplitude the effective mass of the single bands can be determined. Due to many-body interactions we observe enhancements of the effective masses compared to the results by full-potential-density-functional calculations. Therefore, we are able to determine the angular dependence of the interaction strength for the different bands separately.