Spin relaxation under identical Dresselhaus and Rashba coupling strengths in
GaAs quantum wells is studied in both the traditional collinear statistics,
where the energy spectra do not contain the spin-orbit coupling terms, and the
helix statistics, where the spin-orbit couplings are included in the energy
spectra. We show that there is only marginal difference between the spin
relaxation times obtained from these two different statistics. We further show
that with the cubic term of the Dresselhaus spin-orbit coupling included, the
spin relaxation time along the (1,1,0) direction becomes finite, although it is
still much longer than that along the other two perpendicular directions. The
properties of the spin relaxation along this special direction under varies
conditions are studied in detail.Comment: 9 pages, 4 figures. J. Appl. Phys. 99, 2006 (in press