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 theta dependence,, where theta 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 2.34m(0). The result of energy band structure calculation revealed that the conduction bands mainly consist of 3d electrons of Fe atoms.