de Haas–van Alphen Effect in LaFePO with Two-Dimensional Cylindrical Fermi Surfaces

We have succeeded in observing the de Haas–van Alphen (dHvA) effect in LaFePO, the first reported iron-based superconductor in the iron–oxypnictide family. The four detected dHvA frequencies, which correspond to the cross-sectional areas of Fermi surfaces, approximately follow the 1/cos θ dependence, where θ is the field-tilted angle from the [001] direction to the [100] and [110] directions in the tetragonal structure. This indicates that all the Fermi surfaces are nearly cylindrical, with the two-dimensional electronic state. The cyclotron effective mass, which was determined from the temperature dependence of the dHvA amplitude, is relatively large, ranging from 1.82 to 2.34 m 0 . The result of energy band structure calculation revealed that the conduction bands mainly consist of 3 d electrons of Fe atoms.