Technique for measuring infrared cyclotron resonance in ultrahigh magnetic fields

Abstract

A technique is described for giving accurate measurements of cyclotron resonance and Faraday rotation in very high pulsed magnetic fields up to 130 T (1.3 MG). The megagauss fields were generated by the compression of magnetic flux with electromagnetic force in the theta -pinch configuration (Cnare (1966) effect). A tunable CO2 laser was used for the infrared light source, and fast detection of the light was carried out with a high speed infrared detector. A simple method was developed for determining accurately the relative field sensitivity of pickup probes. Based on the calibration of the absolute field sensitivity of the probes by the Faraday rotation of CdS at 632.8 nm, the accuracy of the field intensity measurements reached +or-3%. The cyclotron resonance for electrons in Ge, GaAs and InSb was measured at room temperature.