May 14, 2012

Systematic Approach to find Topological Insulators Using a Master List of 2000 Ingredients to Screen Materials

Physics World - First predicted in 2005 and confirmed in the lab in 2007, topological insulators (TI) are perhaps the hottest material in condensed-matter physics these days. As well as constituting a new phase of quantum matter that should keep physicists busy for some time, the material has recently been shown to harbour quasiparticles resembling Majorana fermions. First predicted by the Italian physicist Ettore Majorana in 1937, such particles could be used to store and transmit quantum information without being perturbed by the outside world. As such, they could find use in the quantum computers of the future.

Researchers at Duke University in the US believe that, until now, discoveries have been based on trial and error.

To encourage a more systematic approach, Stefano Curtarolo and colleagues have created a “master ingredient list” that describes the properties of more than 2000 compounds that could be combined to make TIs. The clever bit of the work is a mathematical formulation that helps database users search for potential TIs that are predicted to have certain desirable properties.

The system is based on Duke’s Materials Genome Repository, which has already been used to develop both scintillating and thermoelectric materials.

According to Curtarolo, the system gives practical advice about the expected properties of a candidate material – for example, whether it will be extremely fragile or robust.

Commenting on the fragile materials, Curtarolo says “We can rule those combinations out because what good is a new type of crystal if it would be too difficult to grow, or if grown, would not likely survive?”

Nature Materials - A search model for topological insulators with high-throughput robustness descriptors

Topological insulators (TI) are becoming one of the most studied classes of novel materials because of their great potential for applications ranging from spintronics to quantum computers. To fully integrate TI materials in electronic devices, high-quality epitaxial single-crystalline phases with sufficiently large bulk bandgaps are necessary. Current efforts have relied mostly on costly and time-consuming trial-and-error procedures. Here we show that by defining a reliable and accessible descriptor , which represents the topological robustness or feasibility of the candidate, and by searching the quantum materials repository, we have automatically discovered 28 TIs (some of them already known) in five different symmetry families. These include peculiar ternary halides, Cs{Sn,Pb,Ge}{Cl,Br,I}3, which could have been hardly anticipated without high-throughput means. Our search model, by relying on the significance of repositories in materials development, opens new avenues for the discovery of more TIs in different and unexplored classes of systems

2 pages of supplemental material
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