Materials Literature
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We propose a topological order parameter for interacting topological insulators, expressed in terms of the full Green's functions of the interacting system. We show that it is exactly quantized for a time reversal invariant topological insulator, and it can be experimentally measured through the topological magneto-el…
An electrostatic quantum dot cannot be formed in monolayer graphene because of the Klein tunneling. However, a dot can be formed with the help of a uniform magnetic field. As shown here, a spatial modulation of the Dirac gap leads to confined states with discrete energy levels, thus defining a dot, without applying ex…
In this work, we experimentally demonstrate a novel and simple approach that uses off-the-shelf optical elements to enhance the collection efficiency from a single emitter. The key component is a solid immersion lens made of diamond, the host material for single color centers. We improve the excitation and detection o…
A series of near-infrared solid-state emitters based on the dicyanoisophorone electron acceptor group was synthesized. The solid-state spectroscopic properties were studied by UV−visible absorption spectroscopy and fluorescence spectroscopy and analyzed in light of the single crystal structures obtained by X-ray diffr…
We describe a test particle approach based on dynamical density functional theory (DDFT) for studying the correlated time evolution of the particles that constitute a fluid. Our theory provides a means of calculating the van Hove distribution function by treating its self and distinct parts as the two components of a…
The current status of research and development of carbon nanotubes (CNTs) electron field emitters is reviewed. The physical aspects of electron field emission that underlie the unique emission properties of CNTs are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are a…
This work defines the crystallinity of cellulose I materials on a dry-weight basis. Theoretical and experimental developments in X-ray diffraction lead to a crystallinity determination method that is estimated to reach 1σ accuracies of better than 0.05 (crystallinity defined between 0 and 1). The method is based on Ri…
A polymer triple-shape memory effect represents one of the most recent discoveries in the rapidly expanding field of shape memory polymers. It refers to the capability of a polymer to memorize two temporary shapes and subsequently recover them, all in one shape memory cycle. Although several examples of triple-shape p…
The effects of applied microwave power, gas flow rate and precursor composition on the substrate-free gas-phase synthesis of graphene were investigated. Graphene was produced through the delivery of ethanol droplets into argon plasmas, and a decrease in the flow rate of the gas used to generate the plasmas resulted in…
We present a derivation of the recently proposed eighth-order phase-field crystal model [A. Jaatinen, Phys. Rev. E 80, 031602 (2009)] for the crystallization of a solid from an undercooled melt. The model is used to study the planar growth of a two-dimensional hexagonal crystal, and the results are compared against si…
In this letter we not only show improvement in the performance but also in the reliability of 30nm thick biaxially strained SiGe (20%Ge) channel on Si p-MOSFETs. Compared to Si channel, strained SiGe channel allows larger hole mobility (μh) in the transport direction and alleviates charge flow towards the gate oxide.…
Many-body quantum-mechanical scattering problem is solved asymptotically when the size of the scatterers (inhomogeneities) tends to zero and their number tends to infinity. A method is given for calculation of the number of small inhomogeneities per unit volume and their intensities such that embedding of these inhomo…
Negatively charged nitrogen-vacancy (NV−) centers in diamond produced by ion implantation often show properties different from NVs created during the crystal growth. We observe that NVs created from nitrogen ion implantation at 30–300 keV show much shorter electron spin coherence time T2 as compared to the “natural” N…
Ultrahigh vacuum (UHV)-deposited films of the mixed phase of tetramethoxypyrene and tetracyanoquinodimethane $({\text{TMP}}_{1}{\text{-TCNQ}}_{1})$ on gold have been studied using ultraviolet photoelectron spectroscopy (UPS), x-ray diffraction (XRD), infrared (IR) spectroscopy, and scanning tunneling spectroscopy (STS…
In this work we investigate possible ferromagnetic order on the graphite surface by using magnetic force microscopy (MFM). Our data show that the tip-sample interaction along the steps is independent of an external magnetic field. Moreover, by combining kelvin probe force microscopy and MFM, we are able to separate th…
We study the electronic states of graphene in piecewise constant potentials using the continuum Dirac equation appropriate at low energies and a transfer matrix method. For superlattice potentials, we identify patterns of induced Dirac points that are present throughout the band structure and verify for the special ca…
Four fundamental dimer manipulations can be used to produce a variety of localized and extended defect structures in graphene. Two-dimensional templates result in graphene allotropes, here viewed as extended defects, which can exhibit either metallic or semiconducting electrical character. Embedded allotropic ribbons—…
Using a combination of theory, experiment, and simulation we investigate the nonlinear response of dense colloidal suspensions to large amplitude oscillatory shear flow. The time-dependent stress response is calculated using a recently developed schematic mode-coupling-type theory describing colloidal suspensions unde…
BiFeO 3 nanoparticles were synthesized by a sonochemical method and their magnetic behavior was investigated both experimentally and theoretically. With an aid of ultrasonic irradiation, the saturated magnetization of BiFeO3 nanoparticles at room temperature was found to be increased effectively, from 0.007 to 0.012 μ…
On a daily basis we are exposed to cationic nanoparticulates in many different ways. They are known to distribute to many organs of the body, and while some evidence suggests that these nanoparticles are toxic to cells, the mechanism of their toxicity is not clear. Here we apply a combination of biochemical and imagin…