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Exotic States Materialize With Supercomputers


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The topological phases in the TMDC materials can be turned on and off by applying a vertical electric field perpendicular to the atomic plane of the material. That's shown here by the red crossing lines that conduct electricity along the edges of the material when the electric field is turned off. When the electric field is turned on, the red lines are broken and a black gap appears between the valence and conducting bands of TMDC, which indicate the edges no longer conduct.

Credit: Qian et. al.

Massachusetts Institute of Technology (MIT) researchers have used Texas Advanced Computing Center's Stampede and Lonestar supercomputers to find a new class of materials that possess an exotic state of matter known as the quantum spin Hall effect.

The computational allocation was made through the Extreme Science and Engineering Discovery Environment (XSEDE), a virtual system scientists use to interactively share computing resources, data, and expertise.

"To me, national computing resources like XSEDE, or specifically the Stampede and Lonestar supercomputers, are extremely helpful to computational scientists," says former MIT researcher Xiaofeng Qian.

In the researchers' purely theoretical work, they used Stampede for part of the calculations that modeled the interactions of atoms in the novel materials, two-dimensional transition metal dichalcogenides (TMDC). The researchers used molecular dynamics simulation software to model a unit cell of atoms. The goal is to find room-temperature quantum spin Hall insulators, which are basically near-two-dimensional materials that block current flow everywhere except along the edges.

The researchers have proposed a topological field-effect transistor, made of sheets of hexagonal boron interlaced with sheets of TMDC. "This is very important because once we have this capability to control the phase transition, we can design some electronic devices that can be controlled easily through electrical fields," Qian says.

From Texas Advanced Computing Center
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