Quantum transistor harnesses new effect
"We found that when deposited in a flat sheet just three atoms thick, our crystalline lattices exhibited a new electronic effect we call the quantum spin Hall effect," professor Xiaofeng Qian told EE Times.
In bulk topological materials like, the transition metal dichalcogenide (TMDC) used here, they conduct on the top and bottom, but are insulators in their interiors. What Qian and colleagues discovered was that when thinned down to just three-atomic-layers thick, they conducted only on the edges and not in the middle. What’s more their conduction could be switched — turned on and off with a gate — like a normal FET just by applying a perpendicular electrical field. Even more unusual, making the TFET a spintronic device, was that the electrons conducting along the edges traveled in different directions depending upon their spin.
"What’s more the electrons with up spin flow in one direction, while those with down spin flow in the opposite direction. So by controlling the injection of charged carriers, we can create a spintronic transistor," Qian told EE Times.
Next Qian and colleagues want to hunt for new materials that exhibit the same or similar characteristics operating at room temperature. He is also handing off his theoretical work to several experimental labs which will build the new TFET in the lab. By combining the TFET with superconductors, Qian hopes experimentalists will achieve the Majorana fermion zero mode — the holy grail of topological quantum computing.
"There is so much opportunity in two-dimensional materials research. Its not just graphene we should be studying, but the many other opportunities in 2-D materials. We expect to be using 2-D materials in real applications in the very near future."
Funding was provided by the U.S. Department of Energy and the NSF.
— R. Colin Johnson, Advanced Technology Editor, EE Times