We investigate the dielectric response of a planar Fermi plasma in the presence of a constant external magnetic field. The conductivity tensor is derived in the random-phase approximation taking into account the effects of the spin of the electron. This proper inclusion of spin makes a significant difference to the results compared with all previous studies, which ignored the intrinsic spin of the electron. In studying the dispersion relations for the electrodynamic modes of the plasma in an external magnetic field, it is necessary to observe that the longitudinal and transverse modes are coupled. These coupled modes are investigated in some detail.

• Received 24 June 1993

DOI:https://doi.org/10.1103/PhysRevB.49.4096