ERA-Chemistry: Spin-polarized topological insulators under pressure

• Applicant: Professor Dr. Michael Ruck
• Subject Area: Solid State and Surface Chemistry, Material Synthesis
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 270024888

Despite the low compressibility of solids, the thermodynamic parameter pressure can notably influence the stability of compounds, their structure and properties. In this proposal we are going to tackle high-pressure modifications of materials that are in focus of the cutting-edge research in solid-state physics, namely topological insulators (TIs). These recently discovered non-magnetic materials represent a new state of matter that enables the quantum spin Hall state at normal conditions. This state supports spatially-separated spin-polarized channels on the bulk surface that can be controlled independently and can transmit information without decoherence. Upon magnetic doping, TIs can exhibit quantized electric current without dissipation, which promises breakthroughs in realization of quantum computing at standard conditions. The number of confirmed TIs is very limited. Some theoretical studies indicate a possibility to obtain new TIs under pressure, but the complementary experimental effort has so far been very scarce. As for magnetic doping of known TIs, experiments under normal pressure have so far yielded very modest substitution rates (2 to 5 at.%) under barely controlled synthetic conditions. In order to fill in these gaps we propose: (a) to explore structural evolution of selected TI-candidates, e. g. layered heterostructures such as BiTeI, (Bi2)n(BiTeI)m, (Bi2)n(Bi2Te3)m, (BiTeI)n(Bi2Te3)m (m, n greater or equal 1) under pressure; (b) to explore possibilities of magnetic substitution for Bi and magnetic intercalation in the confirmed TIs (Bi2Te3, Bi2Se3) and the abovementioned TI-candidates under pressure; 3d-metals (Cu, Mn, Fe, Cr, V) and rare-earth elements (Ce, Gd) will be investigated first; (c) to search for new, probably metastable, structural modifications of BiMX and SbMX, M = S, Se, Te, X = Cl, Br, I, under high-pressure conditions. The proposed research would contribute significantly to solid-state chemistry and physics by increasing the number of TIs and, especially, magnetically-doped ones.

• DFG Programme: Research Grants
• International Connection: Austria
• Partner Organisation: Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Cooperation Partner: Professor Dr. Hubert Huppertz
• Co-Investigator: Professorin Dr. Anna Isaeva