Spin-orbit-split subbands in IV-VI asymmetric quantum wells

Analytical solutions for the spin-orbit-split electron and hole subband structure in IV-VI lead-salt semiconductor asymmetric quantum wells (QW's) are obtained within the envelope function approximation and the Dimmock four-band k.p model for the bulk, around the four equivalent L points. Contrary to the III-V and II-VI QW's, the spin-orbit interaction in the these rocksalt QW's is purely Rashba, although multivalley and anisotropic. The Rashba splitting in these QW's is shown to be highly dependent on the structure parameters and can be much larger than those in similar III-V structures. In particular, specific results for the energy spectrum of Pb1-xEuxTe/PbTe/Pb1-yEuyTe QW's show that the Rashba splitting is approximately linear (and changes sign) with deltaQ, the difference between the band offsets at the two interfaces, independently of the valley and growth direction. The well width and k(parallel to) dependences of the Rashba splitting are also investigated, for the ground and excited states confined in IV-VI QW's, and experimental verification of the main predictions is discussed.