arXiv subjects

J. C. A. Huang

Publications and source records attributed to J. C. A. Huang.

3 recordsLinked to original sources

arXiv2017

NMR studies of the topological insulator Bi2Te3

Te NMR studies were carried out for the bismuth telluride topological insulator in a wide range from room temperature down to 12.5 K. The measurements were made on a Bruker Avance 400 pulse spectrometer. The NMR spectra were collected for the mortar and pestle powder sample and for single crystalline stacks with orientations c parallel and perpendicular to field. The activation energy responsible for thermal activation. The spectra for the stack with c parallel to field showed some particular behavior below 91 K.

cond-mat.mes-hall↗

arXiv2016

Robust topological insulator surface state in MBE grown (Bi_{1-x}Sb_x)_2Se_3

(Bi1-xSbx)2Se3 thin films have been prepared using molecular beam epitaxy (MBE). We demonstrate the angle-resolved photoemission spectroscopy (ARPES) and transport evidence for the existence of strong and robust topological surface states in this ternary system. Large tunability in transport properties by varying the Sb doping level has also been observed, where insulating phase could be achieved at x=0.5. Our results reveal the potential of this system for the study of tunable topological insulator and metal-insulator transition based device physics.

cond-mat.mes-hall↗

arXiv2016

Substrate-induced structures of bismuth adsorption on graphene: a first principle study

The geometric and electronic properties of Bi-adsorbed monolayer graphene, enriched by the strong effect of substrate, are investigated by first-principles calculations. The six-layered substrate, corrugated buffer layer, and slightly deformed monolayer graphene are all simulated. Adatom arrangements are thoroughly studied by analyzing the ground-state energies, bismuth adsorption energies, and Bi-Bi interaction energies of different adatom heights, inter-adatom distance, adsorption sites, and hexagonal positions. A hexagonal array of Bi atoms is dominated by the interactions between the buffer layer and the monolayer graphene. An increase in temperature can overcome a $\sim 50$ meV energy barrier and induce triangular and rectangular nanoclusters. The most stable and metastable structures agree with the scanning tunneling microscopy measurements. The density of states exhibits a finite value at the Fermi level, a dip at $\sim -0.2$ eV, and a peak at $\sim -0.6$ eV, as observed in the experimental measurements of the tunneling conductance.

cond-mat.mtrl-sci↗