Funneling and spin-orbit coupling in transition-metal dichalcogenide nanotubes and wrinkles

Strain engineering provides a powerful means to tune the properties of two-dimensional materials. Accordingly, numerous studies have investigated the effect of bi- and uniaxial strain. Yet, the strain fields in many systems such as nanotubes and nanoscale wrinkles are intrinsically inhomogeneous and the consequences of this symmetry breaking are much less studied. Understanding how this affects the electronic properties is crucial especially since wrinkling is a powerful method to apply strain to two-dimensional materials in a controlled manner. In this paper, we employ density functional theory to understand the correlation between the atomic and the electronic structure in nanoscale wrinkles and nanotubes of the prototypical transition metal dichalcogenide $\mathrm{WSe}_2$. Our research shows that the symmetry breaking in these structures leads to strong Rashba-like splitting of the bands at the $\Gamma$ point and they thus may be utilized in future tunable spintronic devices. The inhomogeneous strain reduces the band gap and leads to a localization of the band edges in the highest-curvature region, thus funneling excitons there. Moreover, we show how wrinkles can be modeled as nanotubes with the same curvature and when this comparison breaks down and further inhomogenities have to be taken into account.Comment: main text 27 pages (preprint style) with 10 figures, attached supplemental material 31 pages (58 in total) with 24 figure

Electron Holographic Mapping of Structural and Electronic Reconstruction at Mono- and Bilayer Steps of h-BN

Here, by making use of medium and high resolution autocorrected off-axis electron holography, we directly probe the electrostatic potential as well as in-plane and out-of-plane charge delocalization at edges and steps in multilayer hexagonal boron nitride. In combination with ab-initio calculations, the data allows to directly reveal the formation of out-of-plane covalent bonds at folded zig-zag edges and steps comprising two monolayers and the absence of which at monolayer steps. The technique paves the way for studying other charge (de)localization phenomena in 2D materials, e.g., at polar edges, topological edge states and defects

Effect of injection angle, density ratio, and viscosity on droplet formation in a microfluidic T-junction

The T-junction microchannel device makes available a sharp edge to form micro-droplets from bio-material solutions. This article investigates the effects of injection angle, flow rate ratio, density ratio, viscosity ratio, contact angle, and slip length in the process of formation of uniform droplets in microfluidic T-junctions. The governing equations were solved by the commercial software. The results show that contact angle, slip length, and injection angles near the perpendicular and parallel conditions have an increasing effect on the diameter of generated droplets, while flow rate, density and viscosity ratios, and other injection angles had a decreasing effect on the diameter

Resistance to the flow for five different stenosis blockage percentages over the midline (r = 1.25 mm) of the blocked vessel at the middle of the simulation, t = 0.5 s, <i>L</i>_{<i>vessel</i>} = 6 <i>cm</i>, <i>R</i>_{<i>vessel</i>} = 1 <i>cm</i>.

<p>Resistance to the flow for five different stenosis blockage percentages over the midline (r = 1.25 mm) of the blocked vessel at the middle of the simulation, t = 0.5 s, <i>L</i>_{<i>vessel</i>} = 6 <i>cm</i>, <i>R</i>_{<i>vessel</i>} = 1 <i>cm</i>.</p

Wall shear stress for a case with blood recirculation ().

<p>Wall shear stress for a case with blood recirculation ().</p

Variation in the resistance to the flow along the midline of the stenosis (r = 2.5 mm) for different time instances in the case with joule heating.

<p>(<b><i>L</i></b>_{<b><i>vessel</i></b>} <b>= 6 <i>cm</i>, <i>R</i></b>_{<b><i>vessel</i></b>} <b>= 1 <i>cm</i></b>, 50 percent stenosis).</p

Profile of the temperature distribution at the stenosis at z = 2 cm for the case without Joule heating at five different time instances, <i>L</i>_{<i>vessel</i>} = 7 <i>cm</i>, <i>R</i>_{<i>vessel</i>} = 1 <i>cm</i> and fifty percent stenosis.

<p>Profile of the temperature distribution at the stenosis at z = 2 cm for the case without Joule heating at five different time instances, <i>L</i>_{<i>vessel</i>} = 7 <i>cm</i>, <i>R</i>_{<i>vessel</i>} = 1 <i>cm</i> and fifty percent stenosis.</p

Modeling and analysis of biomagnetic blood Carreau fluid flow through a stenosis artery with magnetic heat transfer: A transient study - Fig 13

<p><b>(a) to (e).</b> This figure represents recirculation after the stenosis for the case of 60 percent stenosis with a low pressure gradient and Joule heating (a) t = 0 s (b) t = 0.25 s (c) t = 0.5 s (d) t = 0.75 s (e) t = 1 s, <i>L</i>_{<i>vessel</i>} = 6 <i>cm</i>, <i>R</i>_{<i>vessel</i>} = 1 <i>cm</i> and a fifty percent stenosis.</p

Variables in the formulation of the finite volume method in the current formulation.

<p>Variables in the formulation of the finite volume method in the current formulation.</p

Profile of the axial velocity at z = 2 cm for the case without Joule heating at five different time instances, <i>L</i>_{<i>vessel</i>} = 7 <i>cm</i>, <i>R</i>_{<i>vessel</i>} = 1 <i>cm</i> and fifty percent stenosis.

<p>Profile of the axial velocity at z = 2 cm for the case without Joule heating at five different time instances, <i>L</i>_{<i>vessel</i>} = 7 <i>cm</i>, <i>R</i>_{<i>vessel</i>} = 1 <i>cm</i> and fifty percent stenosis.</p