Cyclotron Resonance in the Conduction Band of GaP in Very High Magnetic Fields

Cyclotron resonance in n -type GaP was observed in pulsed high magnetic fields up to 140 T using far-infrared lasers as radiation sources at 119 µm and 337 µm wavelengths. When the magnetic field was applied along the <100> axis, the second resonant peak was observed at 100 T in addition to the first peak at 23 T for a wavelength of 119 µm, the apparent anisotropy factor K * of the effective mass on the assumption of ellipsoidal band model being estimated to be 19±2. For a wavelength of 337 µm, the second peak in the absorption was observed as a broad shoulder centered at 42 T, giving a different value of K * . These observations were interpreted in terms of the camel's back structure model of the conduction band, and the band parameters were determined by a comparison of the data with calculation of the Landau levels.