We report extensive measurements of quantum oscillations in the normal state
of the Fe-based superconductor LaFePO, (Tc ~ 6 K) using low temperature torque
magnetometry and transport in high static magnetic fields (45 T). We find that
the Fermi surface is in broad agreement with the band-structure calculations
with the quasiparticle mass enhanced by a factor ~2. The quasi-two dimensional
Fermi surface consist of nearly-nested electron and hole pockets, suggesting
proximity to a spin/charge density wave instability.Comment: to appear in Physical Review Letter