Topological Dirac states in asymmetric Pb1−xSnxTe quantum wells

Abstract

The electronic structure of lead-salt (IV–VI semiconductor) topological quantum wells (T-QWs) is investigated with analytical solutions of the effective 4x4 Dimmock k ⋅ p model, which gives an accurate description of the bands around the fundamental energy gap. Specific results for three-layer Pb 1 − x Sn x Te nanostructures with varying Sn composition are presented and the main differences between topological and normal (N) QWs highlighted. A series of new features are found in the spectrum of T-QWs, in particular in asymmetric QWs where large (Rashba spin–orbit) splittings are obtained for the topological Dirac states inside the gap. • The band structure of PbSnTe quantum wells from trivial to topological is analyzed. • The Rashba effect for topological Dirac states is analytically discussed. • The spin textures of longitudinal and oblique valley states are obtained.