Fermi Surface of KFe2As2from Quantum Oscillations in Magnetostriction

We present a study of the Fermi surface of KFe2As2 single crystals. Quantum oscillations were observed in magnetostriction measured down to 50 mK and in magnetic fields μ0H up to 14 T. For H ‖ c, the calculated effective masses are in agreement with recent de Haas–van Alphen and ARPES experiments, showing enhanced values with respect to the ones obtained from previous band calculations. For H ‖ a, we observed a small orbit at a cyclotron frequency of 64 T, characterized by an effective mass of ∼ 0.8 me, supporting the presence of a three-dimensional pocket at the Z-point.