A Non-Natural Wurtzite Polymorph of HgSe: A Potential 3D Topological Insulator. Dumett Torres, D., Banerjee, P., Pamidighantam, S., & Jain, P., K. Chemistry of Materials, 29(15):6356-6366, American Chemical Society, 8, 2017.
A Non-Natural Wurtzite Polymorph of HgSe: A Potential 3D Topological Insulator [pdf]Paper  A Non-Natural Wurtzite Polymorph of HgSe: A Potential 3D Topological Insulator [link]Website  doi  abstract   bibtex   
This article demonstrates the power of topotactic synthesis coupled with density functional theory (DFT) for accessing and exploring new phases of matter. Naturally occurring HgSe is a semimetal with a zero gap. Unlike this natural zincblende form of HgSe, our DFT investigations predict that wurtzite HgSe has both an inverted band structure and a band gap, making it a 3D topological insulator (TI). Calculated band structures of HgxCd1–xSe alloys containing strongly relativistic Hg and weakly relativistic Cd show that band gap opening is a consequence of symmetry breaking resulting from a combination of crystal anisotropy and the scalar relativistic effect of Hg electrons. The relativistic contribution of Hg is significant enough in alloys with x ≥ 0.33 for achieving 3D TI behavior at room temperature. We experimentally realize the non-natural wurtzite form by topotactic ion exchange of wurtzite CdSe nanocrystals (NCs), which yields alloy NCs in the range x = 0–0.54 whose measured band gaps follow the pred...

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