arXiv subjects

Zengsheng Ma

Publications and source records attributed to Zengsheng Ma.

6 recordsLinked to original sources

arXiv2021

Intrinsic Spin Hall Conductivity Platform in Triply Degenerate Semimetal

It is generally believed that conductivity platform can only exist in insulator with topological nontrivial bulk occupied states. Such rule exhibits in two dimensional quantum (anomalous) Hall effect, quantum spin Hall effect, and three dimensional topological insulator. In this letter, we propose a spin Hall conductivity (SHC) platform in a kind of three dimensional metallic materials with triply degenerate points around the Fermi level. With the help of a four bands \textbf{k}${\cdot}$\textbf{p} model, we prove that SHC platform can form between $|\frac{3}{2},\pm\frac{3}{2}\rangle$ and $|\frac{1}{2},\pm\frac{1}{2}\rangle$ states of metallic system. Our further ab initio calculations predict that a nearly ideal SHC platform exhibits in an experimentally synthesized TaN. The width of the SHC platform reaches up to 0.56 eV, hoping to work under high temperature. The electrical conductivity tensor of TaN indicates that its spin Hall angle reaches -0.62, which is larger than many previous reported materials and make it an excellent candidate for producing stable spin current.

cond-mat.mes-hall↗

arXiv2018

Structures and Anomalies of Water

Introduction of the principles of the asymmetrical, short-range O:H-O coupled oscillater pair and the basic rule for water ice, which reconciles the structure and anomalies of water ice.

physics.chem-ph↗

arXiv2014

A Supersolid Skin Covering both Water and Ice

The mysterious nature and functionality of water and ice skins remain baffling to the community since 1859 when Farady firstly proposed liquid skin lubricating ice. Here we show the presence of supersolid phase that covers both water and ice using Raman spectroscopy measurements and quantum calculations. In the skin of two molecular layers thick, molecular undercoordination shortens the H-O bond by ~16% and lengthens the OH nonbond by ~25% through repulsion between electron pairs on adjacent O atoms, which depresses the density from 0.92 for bulk ice to 0.75 gcm-3. The O:H-O cooperative relaxation stiffens the H-O stretching phonon from 3200/3150 cm-1 to the same value of 3450 cm-1 and raises the melting temperature of both skins by up to ~310 K. Numerical derivatives on the viscosity and charge accumulation suggests that the elastic, polarized, and thermally stable supersolid phase makes the ice frictionless and water skin hydrophobic and ice like at room temperature.

cond-mat.soft↗

arXiv2013

Mpemba Paradox Revisited -- Numerical Reinforcement

Inspired by responses to the work (arXiv:1310.6514), we solved the one-dimensional, nonlinear Fourier initial and boundary condition problem using the finite element method. Examination of all possible parameters reveals the following: 1. Hydrogen bond has memory effect to emit energy at a rate, or with a relaxation time, depending on initial energy storage. 2. Skin super-solidity creates gradients in thermal diffusion coefficient for heat conduction in liquid with the optimal skin-bulk ratio of 1.48. 3. Convection alone produces no such effect. 4. Mpemba effect happens only in the highly non-diabetic source-path-drain cycling system.

physics.chem-ph↗

arXiv2013

O:H-O Bond Anomalous Relaxation Resolving Mpemba Paradox

We demonstrate that the Mpemba paradox arises intrinsically from the release rate of energy initially stored in the covalent H-O part of the O:H-O bond in water albeit experimental conditions. Generally, heating raises the energy of a substance by lengthening and softening all bonds involved. However, the O:H nonbond in water follows actively the general rule of thermal expansion and drives the H-O covalent bond to relax oppositely in length and energy because of the inter-electron-electron pair coupling [J Phys Chem Lett 4, 2565 (2013); ibid 4, 3238 (2013)]. Heating stores energy into the H-O bond by shortening and stiffening it. Cooling the water as the source in a refrigerator as a drain, the H-O bond releases its energy at a rate that depends exponentially on the initially storage of energy, and therefore, Mpemba effect happens. This effect is formulated in terms of the relaxation time tau to represent all possible processes of energy loss. Consistency between predictions and measurements revealed that the tau drops exponentially intrinsically with the initial temperature of the water being cooled.

physics.chem-ph↗

arXiv2013

Mediation of hydrogen-bond coupling interactions by programmable heating and salting

We show that programmable heating and salting share the same effect on the frequency shift of the O:H and the H-O stretching phonons of the O:H-O hydrogen bond, which revealed that both heating and salting lengthens and softens the O:H bond and shortens and stiffens the H-O bond due to the weakening of the Coulomb repulsion between electron pairs of adjacent oxygen atoms. Understanding provides possible mechanism for the Hofmeister series and the detergent effect on cloth cleaning.

cond-mat.soft↗