K. A. Kokh

Inertness and degradation of (0001) surface of Bi2Se3 topological insulator

Inertness of the cleaved (0001) surface of the Bi2Se3 single crystal, grown by modified Bridgman method, to oxidation has been demonstrated by X-ray photoelectron spectroscopy, scanning tunneling microscopy, and by ab initio DFT calculations. No intrinsic bismuth and selenium oxides are formed on the low-defect, atomically flat Bi2Se3(0001)-(1×1) surface after a long-time air exposure. The inertness of Bi2Se3(0001) to O2 and NO2, as well as bismuth-oxygen bonding formation under molecular adsorption in the Se vacancy was supported by DFT calculations.

Snapshots of Dirac Fermions near the Dirac Point in Topological Insulators

The recent focus on topological insulators is due to the scientific interest in the new state of quantum matter as well as the technology potential for a new generation of THz optoelectronics, spintronics and quantum computations. It is important to elucidate the dynamics of the Dirac fermions in the topologically protected surface state. Hence we utilized a novel ultrafast optical pump mid-infrared probe to explore the dynamics of Dirac fermions near the Dirac point. The femtosecond snapshots of the relaxation process were revealed by the ultrafast optics. Specifically, the Dirac fermion-phonon coupling strength in the Dirac cone was found to increase from 0.08 to 0.19 while Dirac fermions were away from the Dirac point into higher energy states. Further, the energy-resolved transient reflectivity spectra disclosed the energy loss rate of Dirac fermions at room temperature was about 1 meV/ps. These results are crucial to the design of Dirac fermion devices.

Unoccupied topological states on bismuth chalcogenides

The unoccupied part of the band structure of topological insulators Bi

Melt growth of bulk Bi2Te3 crystals with a natural p–n junction

_2

Limiting pump intensity for sulfur-doped gallium selenide crystals

Te

Impact of fs and ns pulses on indium and sulfur doped gallium selenide crystals

_{x}

Experimental Realization of a Topological p-n Junction by Intrinsic Defect Grading.

Se

Systematics of Molecular Self-Assembled Networks at Topological Insulators Surfaces

_{3-x}

Dual nature of magnetic dopants and competing trends in topological insulators

(

Growth and microstructure of heterogeneous crystal GaSe:InS

x=0,2,3