Spin dynamics in (110) GaAs quantum wells under surface acoustic waves

Long spin transport lengths (>60 mu m) independent of temperature up to approximately 80 K are demonstrated in (110) GaAs quantum wells using surface acoustic waves (SAWs). Study of the dynamics of spins aligned along the [110] direction shows that, in addition to the intrinsic absence of the D'yakonov-Perel' spin-relaxation mechanism [Sov. Phys. Semicond.20, 110 (1986)], the Bir-Aronov-Pikus mechanism [Sov. Phys. JETP 42, 705 (1976)] is also suppressed due to the type-II carrier confinement imposed by the SAW piezoelectric potential. Experimental evidence is provided for suppression of the spin relaxation via motional narrowing effects induced by the mesoscopic carrier confinement in narrow stripes along the SAW wave front, thus demonstrating the tuning of the spin-relaxation rates with the acoustic power.