NSF–DMREF: Theory-guided experimental search of new classes of designed topological insulators

Lead investigator: Alex Zunger CU Boulder Colorado 80309 alex.zunger@colorado.edu

Co-Principle Investigators Dan Dessau CU Boulder dan.dessau@colorado.edu, Gang Cao University of Kentucky cao@pa.uky.edu.

Investigators: Qihang Liu, Xiuwen Zhang, Justin Waugh, Xiaoqing Zhou at CU Boulder.

Please see the summary of results and DMREF highlights.group

Project Scope: We accelerate material development by using Functionality-Directed material discovery (also called ‘Inverse Design’) as follows (a) Develop a science-based “Design Principle” (DP) that reflects a target functionality (F) we are searching for (E.g., for F = topological insulation, DP = specific band inversions). (b) Search via DFT for the specific DP in groups of materials in assumes structures (c) Select those that best satisfy the DP and are thermodynamically stable according to DFT. (d) After narrowing down large pools of potential candidates, subject the “best of class” cases to synthesis and characterization of F. Iterations and feedback are used to refine the DP. In the current DMREF we focus on F = Topological insulation and F = Hidden spin polarization described under Technical Progress.

[1]. X. Zhang, Q. Liu, J.W. Luo, A. J. Freeman, A. Zunger,"Hidden spin polarization in inversion-symmetric bulk crystals," Nature Physics 10, 387-393 (2014).

[2] Qihang Liu, Xiuwen Zhang, Hosub Jin, Kanber Lam Jino Im, Arthur J.Freeman and Alex Zunger, "Search and design of nonmagnetic centrosymmetric layered crystals with large local spin polarization" Phys. Rev B 91, 235204 (2015).

[3] Q. Liu, X. Zhang, A. Zunger,"Intrinsic Circular Polarization in Centrosymmetric Stacks of Transition- Metal Dichalcogenide Compounds," Physical Review Letters 114, 087402 (2015).

[4] Q. Liu, X. Zhang, L. B. Abdalla, A. Fazzio, A. Zunger,"Switching a normal insulator into a topological insulator via electric field with application to phosphorene," Nano letters 15, 1222-1228 (2015).