Electronic Raman scattering in a magnetic field

Raman scattering in a magnetic field is proposed as a possible method to solve the problem of whether the light scattering in high-Tc superconductors comes from conduction electrons or not. The electronic Raman light scattering in a magnetic field is studied theoretically. The semiclassical approach based on the system of Boltzmann and Maxwell equations is applied. Two types of resonances in the scattering cross section are found to be from electrons moving along the semiclassical trajectories in a magnetic field. The first one, the cyclotron resonance, is associated with the time dispersion and has the symmetrical logarithmic shape. It is sharp in a clean metal. We show that in a dirty metal the relaxation continuum obtained by Zawadowski and Cardona is modified drastically into the set of smaller continua which are located at the frequencies of simple and multiple cyclotron resonances. The other resonance, associated with the space dispersion, results from the electrons moving coherently with the effective external field. It has the asymmetrical shape. The effects of skin depth and Coulomb interaction are analyzed. The strong peak associated with excitation or absorption of helicons is found in the electronic Raman spectra in a high magnetic field. This peak is considered for the case of dirty metal.