Resumo:
The electron effective g factor tensor in asymmetric III–V semiconductor quantum wells
(AQWs) and its tuning with the structure parameters and composition are investigated with
envelope-function theory and the 8´8 k · p Kane model. The spin-dependent terms in the
electron effective Hamiltonian in the presence of an external magnetic field are treated as a
perturbation and the g factors * ^ g and * g , for the magnetic field in the QW plane and along the
growth direction, are obtained analytically as a function of the well width L. The effects of the
structure inversion asymmetry (SIA) on the electron g factor are analyzed. For the g-factor main
anisotropy D = *- * g g^ g in AQWs, a sign change is predicted in the narrow well limit due to
SIA, which can explain recent measurements and be useful in spintronic applications. Specific
results for narrow-gap AlSb InAs GaSb and AlxGa1-xAs GaAs AlyGa1-yAs AQWs are
presented and discussed with the available experimental data; in particular InAs QWs are shown
to not only present much larger g factors but also a larger g-factor anisotropy, and with the
opposite sign with respect to GaAs QWs.
