A linear magnetoresistance (LMR) with strong temperature dependence and peculiar non-symmetry with respect to the applied magnetic field is observed in high-index (221) Bi 2 Se 3 films. Different from the LMR observed in the previous studies which emphasize the role of gapless linear energy dispersion, this LMR is of disorder origin and possibly arises from the electron surface accumulation layer of the film. Besides, an abnormal negative magneto-resistance that shows a non-monotonic temperature dependence and persists even at high temperatures and in strong magnetic fields is also observed. V

A high-index topological insulator thin film, Bi2 Se3 (221), is grown on a faceted InP(001) substrate by molecular-beam epitaxy (see model in figure (a)). Angle-resolved photoemission spectroscopy measurement reveals the Dirac cone structure of the surface states on such a surface (figure (b)). The Fermi surface is elliptical (figure (c)), suggesting an anisotropy along different crystallographic directions. Transport studies also reveal a strong anisotropy in Hall conductance.

We report the growth of single-domain epitaxial Bi2Se3 films on InP(111)A substrate by molecular-beam epitaxy. Nucleation of Bi2Se3 proceeds at steps, so the lattices of the substrate play the guiding role for a unidirectional crystalline film in the step-flow growth mode. There exists a strong chemical interaction between atoms at the heterointerface, so the growth does not follow the van der Waals epitaxy process. A mounded morphology of thick Bi2Se3 epilayers suggests a growth kinetics dictated by the Ehrlich-Schwoebel barrier. The Schubnikov de Haas oscillations observed in magnetoresistance measurements are attributed to Landau quantization of the bulk states of electrons.

This paper presents an overview of growth of Bi 2 Se 3 , a prototypical three-dimensional topological insulator, by molecular-beam epitaxy on various substrates. Comparison is made between growths of Bi 2 Se 3 (111) on van der Waals (vdW) and non-vdW types of substrates, with the attention paid on twin suppression and strain. Growth along the [221] direction of Bi 2 Se 3 on InP(001) and GaAs(001) substrates is also discussed.

A theoretical analysis of Berry's phases is given for the three-level atoms interacting with external one-mode and two-mode quantized light fields. Three main results are obtained: (i) There is a Berry phase which vanishes in the classical limit or this Berry phase is completely induced by the field quantization; (ii) Berry's phases for the one-mode field and the two-mode field can be equal so long as the photon numbers of the two-mode field are properly chosen; (iii) In the two-mode case, Berry phases of the atom interacting with one mode is affected by the other mode even if the photon number of the other mode is zero.