Widespread spin polarization effects in photoemission from topological insulators
PHYSICAL REVIEW B 84:16 (2011) ARTN 165113
Bulk Fermi surface coexistence with Dirac surface state in Bi_{2}Se_{3}: A comparison of photoemission and Shubnikov–de Haas measurements
PRB American Physical Society 81:20 (2010) 205407
Aharonov-Bohm interference in topological insulator nanoribbons
Nat Mater Nature Publishing Group 9:3 (2010) 225-229
Topological insulator nanowires and nanoribbons.
Nano Lett 10:1 (2010) 329-333
Abstract:
Recent theoretical calculations and photoemission spectroscopy measurements on the bulk Bi(2)Se(3) material show that it is a three-dimensional topological insulator possessing conductive surface states with nondegenerate spins, attractive for dissipationless electronics and spintronics applications. Nanoscale topological insulator materials have a large surface-to-volume ratio that can manifest the conductive surface states and are promising candidates for devices. Here we report the synthesis and characterization of high quality single crystalline Bi(2)Se(3) nanomaterials with a variety of morphologies. The synthesis of Bi(2)Se(3) nanowires and nanoribbons employs Au-catalyzed vapor-liquid-solid (VLS) mechanism. Nanowires, which exhibit rough surfaces, are formed by stacking nanoplatelets along the axial direction of the wires. Nanoribbons are grown along [1120] direction with a rectangular cross-section and have diverse morphologies, including quasi-one-dimensional, sheetlike, zigzag and sawtooth shapes. Scanning tunneling microscopy (STM) studies on nanoribbons show atomically smooth surfaces with approximately 1 nm step edges, indicating single Se-Bi-Se-Bi-Se quintuple layers. STM measurements reveal a honeycomb atomic lattice, suggesting that the STM tip couples not only to the top Se atomic layer, but also to the Bi atomic layer underneath, which opens up the possibility to investigate the contribution of different atomic orbitals to the topological surface states. Transport measurements of a single nanoribbon device (four terminal resistance and Hall resistance) show great promise for nanoribbons as candidates to study topological surface states.Massive Dirac Fermion on the Surface of a Magnetically Doped Topological Insulator
SCIENCE 329:5992 (2010) 659-662