The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

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A comprehensive review of zno materials and devices

Every few years, a new material with unique properties emerges and fascinates the scientific community, typical recent examples being high-temperature superconductors and carbon nanotubes. Graphene is the latest sensation with unusual properties, such as half-integer quantum Hall effect and ballistic electron transport. This two-dimensional material which is the parent of all graphitic carbon forms is strictly expected to comprise a single layer, but there is considerable interest in investigating two-layer and few-layer graphenes as well. Synthesis and characterization of graphenes pose challenges, but there has been considerable progress in the last year or so. Herein, we present the status of graphene research which includes aspects related to synthesis, characterization, structure, and properties.

Graphene: The New Two-Dimensional Nanomaterial

Topological insulators are materials with a bulk excitation gap generated by the spin-orbit interaction that are different from conventional insulators. This distinction is characterized by ${Z}_{2}$ topological invariants, which characterize the ground state. In two dimensions, there is a single ${Z}_{2}$ invariant that distinguishes the ordinary insulator from the quantum spin-Hall phase. In three dimensions, there are four ${Z}_{2}$ invariants that distinguish the ordinary insulator from ``weak'' and ``strong'' topological insulators. These phases are characterized by the presence of gapless surface (or edge) states. In the two-dimensional quantum spin-Hall phase and the three-dimensional strong topological insulator, these states are robust and are insensitive to weak disorder and interactions. In this paper, we show that the presence of inversion symmetry greatly simplifies the problem of evaluating the ${Z}_{2}$ invariants. We show that the invariants can be determined from the knowledge of the parity of the occupied Bloch wave functions at the time-reversal invariant points in the Brillouin zone. Using this approach, we predict a number of specific materials that are strong topological insulators, including the semiconducting alloy ${\mathrm{Bi}}_{1\ensuremath{-}x}{\mathrm{Sb}}_{x}$ as well as $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Sn}$ and HgTe under uniaxial strain. This paper also includes an expanded discussion of our formulation of the topological insulators in both two and three dimensions, as well as implications for experiments.

/pdf/topological-insulators-with-inversion-symmetry-1vaykhe1u1.pdf

Topological insulators with inversion symmetry

We have used the pH-induced self-assembly of a peptide-amphiphile to make a nanostructured fibrous scaffold reminiscent of extracellular matrix. The design of this peptide-amphiphile allows the nanofibers to be reversibly cross-linked to enhance or decrease their structural integrity. After cross-linking, the fibers are able to direct mineralization of hydroxyapatite to form a composite material in which the crystallographic c axes of hydroxyapatite are aligned with the long axes of the fibers. This alignment is the same as that observed between collagen fibrils and hydroxyapatite crystals in bone.

http://science.sciencemag.org/content/sci/294/5547/1684.full.pdf

Self-assembly and mineralization of peptide-amphiphile nanofibers

Nano-optics of surface plasmon polaritons

From measurements of independent elastic moduli it has been shown that the large, modulation wavelength dependent enhancement of the biaxial modulis in composition modulated foils is due to the changes in the primary elastic constants. These results provide an explanation for some of the apparently conflicting data in the literature. The plastic and thermoelectric properties of these materials were also found to be anomalous and wavelength dependent.

Mechanical and Thermoelectric Behavior of Composition Modulated Foils

Equation of state from a phenomenological model for the Kondo system La: Ce

We have synthesized MnSnAs2 single crystals using the vertical temperature gradient solidification method The crystal structure of MnSnAs2 is chalcopyrites, which are “genealogically” related to the more familiar tetrahedrally-coordinated zinc-blende materials, with lattice constants of a = 5794 A, c = 11365 A Using the experimentally determined lattice constants and crystal structure, we carried out first principles electronic structure calculations, using the full-potential linearized augmented plane wave (FLAPW) method in the local density approximation (LDA) The lowest total energies were observed for the AFM state, indicating that AFM ordering in the system is energetically favored at 0 K We find that MnSnAs2 is metallic in the electronic calculation Interestingly, MnSnAs2 exhibited ferromagnetism with TC = 328 K (© 2004 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim)

Electronic and magnetic properties of MnSnAs2

In this paper we demonstrate controlled loading of a closely packed array of optical traps. We also describe the technical advantages of our method of filling the trap array (which makes use of an independent, steerable trap created by a separate objective lens), as well of our specific implementation of array generation by multi-beam interference. Microscopic polystyrene spheres are trapped and subsequently assembled into sites on a two-dimensional optical lattice, which is formed from the interference of two pairs of coherent laser beams via an optical setup that allows for simple, continuous variation of lattice parameters over a very wide range. Individual particles in the initial assembly are dynamically manipulated with the independent laser beam, which offers the freedom to generate either defect-free lattices or a lattice with designer defects. As examples we demonstrate the assembly of a defect-free square lattice and a lattice with a single vacancy.

https://iopscience.iop.org/article/10.1088/1367-2630/8/5/070/pdf

John B Ketterson

Papers

Mechanical and Thermoelectric Behavior of Composition Modulated Foils

Equation of state from a phenomenological model for the Kondo system La: Ce

Electronic and magnetic properties of MnSnAs2

Dynamic Control of Defects in a Two-dimensional Optically Assisted Assembly

Ultrasonic attenuation in Thallium