Tipping effects in Azbel-Kaner cyclotron resonance

Abstract

Calculations of Azbel-Kaner line shapes when the magnetic field is tipped out of the surface have been carried out in a number of cases for both the free electron model and an arbitrary Fermi surface with mass spread. For small angles of tip the results substantiate the Doppler shift theory advanced by Koch, Stradling & Kip and provide a consistent explanation of the observed peak shifts or splitting in all cases. Arguments are presented that at larger tip angles the overall absorption will decrease with increasing field, and the original resonance may become inverted, owing to the removal of non-stationary electrons from the skin depth. At large tip angles (5° or so) inverted and doubled resonances observed with parallel polarization are shown to arise from ‘field splashes’ set up by drifting electrons from the limiting points, regardless of the nature of the Fermi surface. Apparently normal resonances observed at very large tip angles are shown to arise from so-called ‘cylinder sections’ where dA/dk²_H = 0 and v_D = 0, A and v_D being the area of the orbit in k space and the drift velocity respectively.