An experimental study of helicon resonance in metals

This review is devoted to helicons-electromagnetic waves propagating in the electron-hole plasma in metals at low temperatures. The review is divided into two parts. In the first part the author presents the theory of, and the experimental data on, helicons in the absence of effects caused by Landau quantisation of conduction electron energy in a strong magnetic field. The author emphasises the peculiar features of helicon propagation which are due to the anisotropy of the electron spectrum of metals, effects not observable in a gaseous plasma. An analysis of data on the anisotropy of the collision damping, the Landau damping and on dopplerons-a new branch of electromagnetic excitations in the vicinity of the Doppler-shifted cyclotron resonance-is given. He also discusses the results of studies of the acoustic satellites of helicon resonance and the peculiarities of helicon propagation in the intermediate state of type-I superconductors. In the second part he presents the results of observations of new effects caused by Landau quantisation, namely oscillations of the phase velocity of helicons, non-linear helicon resonance and the anomalous attenuation of helicons in metals with diamagnetic domains. Examples are discussed in which the helicon resonances are employed to investigate transport relaxation in high magnetic fields, the production of defects by plastic deformation, open orbits and the absolute amplitude of the de Haas-van Alphen effect.