Observation of cyclotron resonance and measurement of the hole mass in optimally doped La 2 − x Sr x CuO 4

Using time-domain terahertz spectroscopy in pulsed magnetic fields up to 31 T, we measure the terahertz optical conductivity in an optimally doped thin film of the high-temperature superconducting cuprate La1.84Sr0.16CuO4. We observe systematic changes in the circularly polarized complex optical conductivity that are consistent with cyclotron absorption of p-type charge carriers characterized by a cyclotron mass of 4.9m(e) +/- 0.8m(e) and a scattering rate that increases with magnetic field. These results open the door to studies aimed at characterizing the degree to which electron-electron interactions influence carrier masses in cuprate superconductors.