Observation of cyclotron resonance in rare-earth monopnictides microwave region Original Research Article

We have directly determined the cyclotron effective masses of RX (R=La,Gd, X=As,Sb,Bi) by means of cyclotron resonance measurements at the frequency range between 56 and 190 GHz in the temperature range from 50 to 0.5 K. In addition to normal cyclotron resonance, two anomalous absorption lines are observed for the high-quality single crystal of LaSb, which shows quadratic behavior on the frequency–field diagram.