Coherent Single Spin Source based on topological insulator

We report on the injection of quantized pure spin current into quantum conductors. In particular, we propose an on demand single spin source generated by periodically varying the gate voltages of two quantum dots that are connected to a two dimensional topological insulator via tunneling barriers. Due to the nature of the helical states of the topological insulator, one or several {\it spin pair}s can be pumped out per cycle giving rise to a pure quantized alternating spin current. Depending on the phase difference between two gate voltages, this device can serve as an on demand single spin emitter or single charge emitter. Again due to the helicity of the topological insulator, the single spin emitter or charge emitter is dissipationless and immune to disorders. The proposed single spin emitter can be an important building block of future spintronic devices.Comment: 5 pages, 4 figures, append one co-author that has been misse

Comparison of Tetrel Bonds in Neutral and Protonated Complexes of PyridineTF3 and FuranTF3 (T = C, Si, and Ge) with NH3

Ab initio calculations have been performed for the complexes H+–PyTX3⋯NH3 and H+–furanTF3⋯NH3 (T = C, Si, and Ge; X = F and Cl) with focus on geometries, energies, orbital interactions, and electron densities to study the influence of protonation on the strength of tetrel bonding. The primary interaction mode between α/β-furanCF3/p-PyCF3 and NH3 changes from an F⋯H hydrogen bond to a C⋯N tetrel bond as a result of protonation. Importantly, the protonation has a prominent enhancing effect on the strength of tetrel bonding with an increase in binding energy from 14 to 30 kcal mol−1. The tetrel bonding becomes stronger in the order H+–p-PySiF3⋯NH3 \u3c H+–m-PySiF3⋯NH3 \u3c H+–o-PySiF3⋯NH3, showing a reverse trend from that of the neutral analogues. In addition, there is competition between the tetrel and hydrogen bonds in the protonated complexes, in which the hydrogen bond is favored in the complexes of H+–p-PyCF3 but the tetrel bond is preferred in the complexes of H+–p-PyTX3 (T = Si, Ge; X = F, Cl) and H+–o/m-PySiF3

p-Laplace equations in conformal geometry

In this paper we introduce the p-Laplace equations for the intermediate Schouten curvature in conformal geometry. These p-Laplace equations provide more tools for the study of geometry and topology of manifolds. First, the positivity of the intermediate Schouten curvature yields the vanishing of Betti numbers on locally conformally flat manifolds as consequences of the B\"{o}chner formula as in the works of Nayatani and Guan-Lin-Wang. Secondly and more interestingly, when the intermediate Schouten curvature is nonnegative, these p-Laplace equations facilitate the geometric applications of p-superharmonic functions and the nonlinear potential theory. This leads to the estimates on Hausdorff dimension of singular sets and vanishing of homotopy groups that is inspired by and extends the work of Schoen-Yau. In the forthcoming paper we will present our results on the asymptotic behavior of p-superharmonic functions at singularities.Comment: 19 pag

On the asymptotic behavior of p-superharmonic functions at singularities

In this paper we develop the p-thinness and the p-fine topology for the asymptotic behavior of p-superharmonic functions at singular points. We consider these as extensions of earlier works on superharmonic functions in dimension 2, on the Riesz and Log potentials in higher dimensions,, and on p-harmonic functions. It is remarkable that, contrary to the above cases, the p-thinness for the singular behavior differs from the p-thinness for continuity by the Wiener criterion for p-superharmonic functions. As applications of asymptotic estimates of p-superharmonic functions, we also obtain asymptotic estimates of solutions to a class of fully nonlinear elliptic equations. This paper grows out of our recent papers on the potential theory in conformal geometry.Comment: 26 page

Benzimidazolium 2-(2,4-dichloro­phen­oxy)acetate monohydrate

In the crystal of the title hydrated mol­ecular salt, C7H7N2 +·C8H5Cl2O3·H2O, the components inter­act by way of N—H⋯O and O—H⋯O hydrogen bonds, leading to chains propagating in [100]