We report a comparison of conduction electron spin-splitting in III-V quantum wells caused by asymmetric band edges with that due to applied electric field. Measurements in GaAs/AlGaAs quantum wells and calculations on a range of heterostructures, both symmetric and asymmetric, lead to the conclusion that in a heterostructure with nearly “isomorphous” band edges (i.e., with conduction and valence band-edge potentials related by a constant factor, exemplified by GaAs/AlGaAs) spin splittings will be unmeasurably small even in a highly asymmetric structure. Application of an external electric field or the presence of a Hartree potential gradient in the system will generally break isomorphism and therefore produce a significant spin splitting.

• Received 14 May 2010

DOI:https://doi.org/10.1103/PhysRevB.82.045317