We report infrared studies of the insulator-to-metal transition (IMT) in GaAs doped with either magnetic (Mn) or nonmagnetic acceptors (Be). We observe a resonance with a natural assignment to impurity states in the insulating regime of Ga1−xMnxAs, which persists across the IMT to the highest doping (16%). Beyond the IMT boundary, behavior combining insulating and metallic trends also persists to the highest Mn doping. Be-doped samples, however, display conventional metallicity just above the critical IMT concentration, with features indicative of transport within the host valence band. B. C. Chapler, R. C. Myers, S. Mack, A. Frenzel, B. C. Pursley, [ Read More ]
In the recently discovered class of materials known as topological insulators, the presence of strong spin-orbit coupling causes certain topological invariants in the bulk to differ from their values in vacuum. The sudden change in invariants at the interface results in metallic, time reversal invariant surface states whose properties are useful for applications in spintronics and quantum computation. However, a key challenge is to fabricate these materials on the nanoscale appropriate for devices and probing the surface. To this end we have produced 2 nm thick nanocrystals of the topological insulator Bi2Se3 via mechanical exfoliation. For crystals thinner than 10 nm [ Read More ]
Professor Ken Burch just after his talk, The Scotch Tape Method: Moving Beyond Graphene, at the Connaught Summer Institute in Nanofabrication, June 3–11, 2011 June 6, 2011 Prof. Ken Burch from U of T Engineering on Vimeo.
Open Positions for Postdoctoral, Graduate and Undergraduate Students. If interested contact: kburch@physics.utoronto.ca
L. J. Sandilands, J. X. Shen, G. M. Chugunov, S. Y. F. Zhao, Shimpei Ono, Yoichi Ando, K. S. Burch. Stability of exfoliated $Bi_2Sr_2Dy_xCa_1-xCu_2O_8+δ$ studied by Raman microscopy Phys. Rev. B 82, 064503 (2010)
