The polarization and piezoelectric response of the BiTeX (X=Cl,Br,andI) layered tellurohalides are computed from first principles. The results confirm a mixed ionic-covalent character of the bonding, and demonstrate that the internal structure within each triple layer is only weakly affected by the external stress, while the changes in the charge distribution with stress produce a substantial negative piezoelectric response. This suggests a mechanism for negative piezoelectric response that should remain robust even in the ultrathin film form in this class of materials.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics