Electronic Structure of Y and Lu Borocarbides Determined by de Haas—van Alphen Experiments

Abstract

The Fermi surfaces of the nonmagnetic borocarbide superconductors YNi2B2C and LuNi2B2C were studied by the de Haas — van Alphen (dHvA) effect. Several branches of dHvA frequencies were observed in the normal state for B ‖ c on single crystals of both systems. The observed dHvA frequencies and their angular dependencies are very similar indicating the same topology of the corresponding parts of the Fermi surfaces. Together with the effective cyclotron masses m c and the Fermi velocities vF, the results were discussed in the context of electronic band structure calculations. In both systems magnetoquantum oscillations were also observed in the superconducting state below the upper critical field Bc2. The additional damping of the dHvA oscillations in the vortex state strongly depends on the extremal orbit taken into consideration.