QUANTUM THEORY OF DYNAMIC MAGNETORESISTANCE.
OREGON UNIV EUGENE DEPT OF PHYSICS
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The connected-diagram expansion method is applied in the evaluation of the dynamic conductivity of an electron-impurity system subjected to a constant magnetic field B. This method treats the two cases, B does not 0 and B 0, on the same footing such that the differences appear at the final stage of calculation. A clear physical picture is sustained throughout because no extraneous arguments about the splitting of a density operator into diagonal and non-diagonal parts in free-electron states, which appeared in most of the past literatures, are used. A transport equation in the limits of low impurity density n sub s and small coupling lambda is given explicitly. This equation is meant to describe the dynamic conductivity at an arbitrary frequency omega of an applying electric field and at an arbitrary magnitude of B. It reduces to the transport equation of Argyres in the limit of zero frequency and to that of Yamada-Ron in the limit of zero field. The conductivity in the limits of large omega, large B, small n sub s and small lambda, is calculated explicitly. The limiting forms of the new expressions are in agreement with the result of Titeica B 0, omega 0 and with that of Yamada-Ron B 0, omega does not 0. The expression explicitly indicates that the dynamical response can be no more interpreted in terms of scattering cross section. The conductivity of an electron-phonon system is discussed briefly. Author
- Electricity and Magnetism
- Quantum Theory and Relativity