Determination of Cyclotron Effective Masses on LaSb

Cyclotron resonance (CR) measurements on a single crystal of LaSb have been performed in the c temperature range from 1.6K to 40K in the frequency range from 50 to 190GHz. We have observed three CR absorption lines at low temperature. For magnetic fields parallel to the [100] direction, the determined effective masses are 0.20 +/- 0.02m(0), 0.17 +/- 0.02m(0), and 0.45 +/- 0.04m(0), which correspond to the alpha-branch, the beta-branch, and the gamma-branch, respectively.