Abstract
We investigate theoretically the PbTe/PbSnTe heterostructure grown in the [111] direction, specifically a quantum wall (potential step of width ) of PbTe embedded in PbSnTe. For large enough to lead to band inversion and for large , there are well-known gapless interface states associated with four valleys. We show that for nm, the three pairs of states from oblique valleys strongly couple and become gapped with a gap 10 meV. On the other hand, the interface states from the [111] valley are essentially uncoupled, and they retain their helical character, remaining analogous to states at surfaces of thin layers of three-dimensional topological insulators. This opens up a possibility of studying the physics of two-dimensional helical Dirac fermions in heterostuctures of already widely studied IV-VI semiconductors.
- Received 15 February 2012
DOI:https://doi.org/10.1103/PhysRevB.85.205319
©2012 American Physical Society