INSTABILITY IN THE QUANTUM HELICON DISPERSION RELATION.
Technical rept. no. 21,
CALIFORNIA UNIV SAN DIEGO LA JOLLA
Pagination or Media Count:
When a quantum gas in a magnetic field is treated with all electromagnetic interactions, at very low temperatures it becomes unstable against transverse excitations propagating in the direction of the field. This instability appears as a root of the quantum helicon dispersion relation in the upper half frequency plane. It is shown that the instability is due to the failure of the conventional Hartree ground state in which the one electron states are the ordinary Landau ones to minimize the ground state energy, when magnetic currentcurrent interactions are retained along with the Coulomb interactions. A state was found giving a lower energy than the conventional one, in which transverse volume currents exist perpendicular to the magnetic field. Because, however, the magnetic coupling is very weak, the reduction in energy is unobservably small at any realistic field strengths or electronic densities. It is concluded that the instability does not lead to any measurable effects, and that for all practical purposes the conventional thermal equilibrium state can be regarded as stable. Author