Harmonics of the cyclotron resonance in the organic superconductor β-(BEDT-TTF)2IBr2

Cyclotron resonance, along with several harmonics, has been observed in the magneto-optical response of the organic superconductor β-(BEDT-TTF)2IBr2. We compare the effective mass obtained from magneto-optical experiments with previous magnetic quantum oscillation (thermodynamic) measurements. Other resonances observed in this sample have a different angular behaviour from cyclotron resonance; the origins of these resonances are discussed and compared with previous experiments.