Negative Transport Lifetime of Electrons in Quantum Wires

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Abstract
In bulk and 2D structures, the ensemble average transport lifetime of electrons can only be a positive quantity. However, in quasi 1D structures, it can sometimes become negative. The negative sign is manifested whenever forward scattering due to acoustic phonon absorption is the dominant electron interaction. The magnitude of this negative lifetime can be increased severalfold by the application of a magnetic field which preferentially suppresses backscattering over forward scattering. Negative transport lifetimes can result in runaway electron drift (ultimately arrested by the onset of other scattering mechanisms) and possibly velocity overshoot at very low electric fields.