  Based on a Monte Carlo method, we investigate the influence of transport
conditions on the electron spin relaxation in GaAs. The decay of initial
electron spin polarization is calculated as a function of distance under the
presence of moderate drift fields and/or non-zero injection energies. For
relatively low fields (a couple of kV/cm), a substantial amount of spin
polarization is preserved for several microns at 300 K. However, it is also
found that the spin relaxation rate increases rapidly with the drift field,
scaling as the square of the electron wavevector in the direction of the field.
When the electrons are injected with a high energy, a pronounced decrease is
observed in the spin relaxation length due to an initial increase in the spin
precession frequency. Hence, high-field or high-energy transport conditions may
not be desirable for spin-based devices.
