Tuesday, September 27, 2011
Helical Dirac fermions on the surface topological insulators are a new class of electronic states that could enable dissipation-free spintronics and robust quantum information processors. Our recent study of the influence of disorder on these states shows that although they are resilient against backscattering, fluctuations caused by charge impurities could cause problems for such applications. Using spectroscopic imaging with the scanning tunneling microscope, we show that disorder can result in pronounced nanoscale spatial fluctuations of energy, momentum and helicity of these electronic states near the Dirac point. Reducing charge defects will be required for both tuning the chemical potential to the Dirac energy and achieving high electrical mobility for these novel states.
Published in Nature Physics: "Spatial fluctuations of helical Dirac fermions on the surface of topological insulators," Haim Beidenkopf, Pedram Roushan, Jungpil Seo, Lindsay Gorman, Ilya Drozdov, Yew San Hor, R. J. Cava, and Ali Yazdani, Nature Physics 7, 939 (2011). (Letter)