Valence band spin splitting in strained In0.18Ga0.82As/GaAs quantum wells

Abstract

Magneto-transport at low temperature has been employed to study a series of p-type In_0.18Ga_0.82As/GaAs quantum wells with carrier concentrations in the range (1.5-4.3)*10¹¹ cm^-2. Tilting the field from the growth direction does not change the relative magnitudes of the spin-split conductivity minima. This is a remarkable effect, and confirms the recent results of Martin et al. (see Phys. Rev. B, vol.42, p.9237, 1990) on an In_0.15Ga_0.85Sb/GaSb quantum well. Strain decoupling of the mod M_J mod =³/₂ and mod M_J mod =¹/₂ states projects the spin onto the growth direction. The authors find here that this effect occurs for the nu =3, 4 and nu =5, 6 and nu =7, 8 spin-split conductivity minima. The Shubnikov-de Haas oscillations in perpendicular field have been compared to the Landau levels calculated with an eight-band k.p model and this determines an upper limit to the value of kappa _l, the spin-magnetic-field coupling parameter.