ZERO-MAGNETIC-FIELD SPIN SPLITTINGS IN ALXGA1-XAS GAAS HETEROJUNCTIONS/

The observation of zero-magnetic-field spin splitting of the lowest el ectron subband in an AlxGa1-xAs/GaAs heterojunction, detected as a bea ting pattern in the Shubnikov-de Haas oscillations, is reported. The o bserved effect is induced by a combination of the bulk k(3) term, ascr ibed to the inversion asymmetry of the host crystal and the spin-orbit Rashba term, H-so=alpha(sigma xk). z, introduced by the electric fiel d at the AlxGa1-xAs/GaAs interface. The magnitude of the spin splittin g depends on both the built-in electric field and the electron concent ration in the two-dimensional electron gas.