Electrically tunable surface-to-bulk coherent coupling in topological insulator thin films

• Main Authors: Steinberg, Hadar (Contributor), Laloe, Jean-Baptiste (Contributor), Fatemi, Valla (Contributor), Moodera, Jagadeesh (Contributor), Jarillo-Herrero, Pablo (Contributor)
• Other Authors: MIT Materials Research Laboratory (Contributor), Massachusetts Institute of Technology. Department of Physics (Contributor), Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology) (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society (APS), 2012-03-08T18:56:17Z.
• Subjects: Article
• Online Access: Get fulltext

We study coherent electronic transport in charge-density-tunable microdevices patterned from thin films of the topological insulator (TI) Bi[subscript 2]Se[subscript 3]. The devices exhibit pronounced electric field effect, including ambipolar modulation of the resistance with an on-and-off ratio of 500%. We show that the weak antilocalization correction to conductance is sensitive to the number of coherently coupled channels, which in a TI includes the top and bottom surfaces and the bulk carriers. These are separated into coherently independent channels by the application of gate voltage and at elevated temperatures. Our results are consistent with a model where channel separation is determined by a competition between the phase coherence time and the surface-to-bulk scattering time.
Israel. Ministry of Science
National Science Foundation (U.S.). Division of Materials Research (Grant No. 0504158)
United States. Office of Naval Research (Grant No. N00014-09-1-0177)
David & Lucile Packard Foundation (Packard Fellowship)