New mechanisms of cyclotron resonance in metals in oblique magnetic fields

Abstract

Two new mechanisms of cyclotron resonance in metals in an oblique magnetic field were theoretically studied. In contrast to the resonant effect in a metal surface parallel to a magnetic field, which develops as a result of repeated return of electrons to the skin-layer, the proposed resonance mechanisms are associated with the existence of “current sheets” at great distances from the surface of the metal. The mechanism of current bursts is caused by a “chain” of trajectories of electrons that do not drift deep into the metal. Resonance occurs at the multiple frequencies ω = nΩ o and satisfies the values of the cyclotron frequency Ω at the extremal cross-sections of the Fermi surface. The width and form of the resonance curves are not determined by the collision frequency, but by the diameter dispersion of the resonant electrons. The other resonance mechanism, observed by k ip and his associates, 9 is caused by the development of current sheets due to the drift of electrons within the metal. Resonance occurs at the frequencies ω = (n/2)Ω, where n represents the integral and Ω represents the cyclotron frequency of the electrons with an extremal displacement during the period along the magnetic field. In the case of a complex Fermi surface, resonance occurs, generally speaking, in the case of any angle of inclination. The resonant impedance anomalies-possess a logarithmic nature, while their width is determined by the collisions. In both cases the resonant lines are inverted as compared to the curves in a parallel field which is associated with the increase of the effective depth of penetration of the electromagnetic field in the metal.