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1. chinaXiv:202205.00002 [pdf]

Large-scale ultra-fast strain engineering of CVD-grown two-dimensional materials on strain self-limited deformable nanostructures towards enhanced field effect transistors

Zheng Huang; Nan Lu; Zifeng Wang; Shuoheng Xu; Jie Guan; Yaowu Hu
Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties

Strain engineering of 2D materials is capable of tuning the electrical and optical properties of the materials without introducing additional atoms. However, there are still great challenges in realizing straining of 2D materials with CMOS compatibility. Here, a method for large-scale ultrafast strain engineering of CVD-grown 2D materials is proposed. We introduce locally non-uniform strains through the cooperative deformation of materials and metal/metal oxide core/shell nanoparticles through cold laser shock. Raman and PL spectra reveal that the tensile strain of MoS2 changes and the band gap decreases after laser shock. MD simulations are used to investigate the mechanism of the ultrafast straining of CVD-grown 2D materials. Field effect transistors of CVD MoS2 were fabricated, and the performances before and after straining of the same devices are compared. By adjusting the strain level of MoS2, the field effect mobility can be increased from 1.9 cm2V-1s-1 to 44.1 cm2V-1s-1. This is the maximum value of MoS2 FETs grown by CVD with SiO2 as dielectric. As an environment-friendly, large-scale and ultra-fast manufacturing method, laser shock provides a universal strategy for large-scale adjustment of 2D materials strain, which will help to promote the manufacturing of 2D nano electronic devices and optoelectronic devices.

 

submitted time 2022-04-30 Hits1624Downloads214 Comment 0

2. chinaXiv:202204.00025 [pdf]

Co-positivity of tensors and Stability conditions of two Higgs potentials

宋义生
Subjects: Physics >> The Physics of Elementary Particles and Fields

We give how to calculate the vacuum stability  conditions of scalar potential for two Higgs doublet model with explicit CP conservation. Moreover, the analytical sufficient and necessary conditions are obtained. The argument methods are first used to study the tensor with two parameters.

submitted time 2022-04-02 Hits1982Downloads275 Comment 0

3. chinaXiv:202202.00008 [pdf]

非互易 Aubry-Andr\'e 模型的经典电路模拟

成恩宏 (Enhong Cheng); 郎利君 (Li-Jun Lang)
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
Subjects: Physics >> Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology

非厄米的引入扩展了传统厄米量子系统中的概念并诱导出许多新奇的物理现象, 比如非厄米系统所独有的非厄米趋肤效应, 这使得对非厄米量子模型的模拟成为大家关注的热点. 相比于量子平台, 经典系统具有成本低廉、技术成熟、室温条件等优势, 而其中的经典电路系统则更加灵活, 原则上可以模拟任意维度、任意格点间跃迁、任意边界条件下的量子紧束缚模型, 已经成为模拟量子物态的有力平台. 本文利用经典电路通过 SPICE 成功模拟了一个重要的非厄米量子模型 —— 非互易 Aubry-Andr\'e 模型 —— 的稳态性质, 此模型同时具有非互易的格点跃迁和准周期的格点在位势. 以此为例, 详细介绍了如何建立经典电路的拉普拉辛形式与量子紧束缚模型哈密顿矩阵在不同边界条件下的映射, 尤其是如何利用电流型负阻抗变换器构建模型的非互易性. 然后, 根据电路的格林函数, 通过 AC 电流驱动并测量电压响应的方式, 用 SPICE 模拟了周期边界条件下的复能谱和相应的能谱缠绕数, 以及开边界条件下的趋肤与局域模式的竞争. 其中, 为了使电路的响应不发散, 本文还解析地给出辅助元件的设置原则. 结果显示, SPICE 模拟与理论计算很好地吻合, 为进一步的实验实现提供了详细的指导. 由于本文电路设计与测量方案的普适性, 原则上可以直接应用于其他非厄米量子模型的电路模拟. 

submitted time 2022-03-24 Hits2811Downloads434 Comment 0

4. chinaXiv:202203.00008 [pdf]

A Statistical Fields Theory underlying the Thermodynamics of Ricci Flow and Gravity

罗敏杰
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The paper proposes a statistical fields theory of quantum reference

frame underlying the Perelman's analogies between his formalism of

the Ricci flow and the thermodynamics. The theory is based on a $d=4-\epsilon$

quantum non-linear sigma model (NLSM), interpreted as a quantum reference

frame system which a to-be-studied quantum system is relative to.

The statistic physics and thermodynamics of the quantum frame fields

is studied by the density matrix of them obtained by the Gaussian

approximation quantization. The induced Ricci flow of the frame fields

and the Ricci-DeTurck flow of the frame fields associated with the

density matrix is deduced. In this framework, the diffeomorphism anomaly

of the theory has deep thermodynamic interpretation. The trace anomaly

is related to a Shannon entropy in terms of the density matrix, which

monotonically flows and achieves its maximal value at the flow limit,

called the Gradient Shrinking Ricci Soliton (GSRS). A relative Shannon

entropy w.r.t. the maximal entropy gives a statistical interpretation

to Perelman's partition function, which is also monotonic and giving

an analogous H-theorem to the statistical frame fields system. We

find that a temporal static 3-space of the GSRS spacetime is in a

thermal equilibrium state, and Perelman's analogies between his formalism

and the thermodynamics of the frame fields in equilibrium can be explicitly

given in the framework. As a possible underlying microscopic theory

of the gravitational system, the theory is also applied to understand

the thermodynamics of the Schwarzschild black hole. The cosmological

constant in the effective theory of gravity at cosmic scale is also

briefly given.

submitted time 2022-03-03 Hits2432Downloads474 Comment 0

5. chinaXiv:201610.00003 [pdf]

相对的时空标度和绝对的时空背景

Chen, Chiyi
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics
Subjects: Astronomy >> Galaxy and Cosmology

本文以物理学中标准钟和标准尺的定义实质和爱因斯坦的相对论物理为基础,从自然哲学层次出发讨论了物理的时空观。提出在已有的时空标度的概念基础上,应该进一步明确区分时空标度和时空背景。根据爱因斯坦相对论的实际逻辑可以作如下理解,满足相对论性变化的是时空标度,而时空标度是人为地根据物质实体中发生或存在的固有物理事件定义的,时空背景作为反映时空标度的长短或大小变化的必备基础和参考背景,应该是绝对的。空间标度的长短尺度在本质上应该理解为固有物理事件在空间的绝对背景上截取的线段的长度。最后以此时空观为基础,探讨了经典力学框架下的质点动力学方程,自然地得出了新形式的质点动力学方程。新动力学方程可以直接应用到任何实际的,(相对宇宙绝对背景)无转动的参考系中。而惯性力的本质正是作用到参考物体上的真实受力。这一经典质点动力学改造的本质是修正了牛顿第二定律传统体系中存在的一个理论缺陷。然而,可能更为重要的是,在形式上具备明显优越性的新质点动力学方程反过来强烈地暗示了时空背景的绝对性。文章最后结合广义相对论的引力几何化思想,探讨了引力对时空标度的物理效应。

submitted time 2022-02-04 Hits4329Downloads549 Comment 0

6. chinaXiv:202201.00124 [pdf]

关于质点动力学的相对性原理的探索

陈驰一
Subjects: Physics >> Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics

本文着重探索了质点动力学的相对性原理的物理逻辑。通过动力学的因果分析,发现牛顿第二定律之所以存在惯性系和惯性力疑难,根本原因是忽略了参考系动力学的因果对应。参考系的动力学性质应该归结到参考质点上,而人为划分的参考质点和被考察质点在动力学中应该处于完全平等的地位,由此构建出一个不依赖惯性系,且在所有平动参考系保持形式不变的质点动力学方程。至于转动参考系,一方面,惯性力的本质经新形式的质点动力学方程揭示为参考质点的经过质量平权以后的真实受力,已经可以明确和引力在物理上不等效。另一方面,根据因果对应的基本法则,融入转动参考系的物理则必须包含四个不共面参考质点的受力和运动学信息,因此无法和平动参考系中的新形式质点动力学方程统一成一个简洁的方程形式。最后本文提议所有声称已推广到转动参考系的相对性原理值得重新审视,小心求证。

submitted time 2022-01-29 Hits3847Downloads409 Comment 0

7. chinaXiv:202201.00098 [pdf]

新疆草地生态系统健康评价体系构建

陈春波
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

草地是重要的陆地生态系统类型,草地生态系统健康评价是干旱区草地健康研究的重要组成部分。新疆位于中亚干旱区,典型的“山盆”地形结构孕育的天然草地具有鲜明的垂直地带性,又因水热组合差异形成了丰富多样的草地类型,这使得新疆草地生态系统健康评价成为一项系统的复杂工作,急需构建适用于新疆的草地生态系统健康评价体系。本研究以新疆草地生态系统为研究对象,构建新疆草地生态系统健康评价总体框架,从数据来源与评价方法阐述了新疆草地生态系统健康评价体系。基于草地样方、生物气象与多源遥感数据建立草地生态系统基础数据库,针对草地健康评价方法,明确评价目标,确定评价区域与参照系统,进而筛选评价指标,最后通过选择评价方法开展草地健康评价,采用四分法将评价结果划分为健康、亚健康、警戒与崩溃。采用该体系在新疆和田地区民丰县开展草地生态系统健康评价,结果显示围栏内的温性荒漠类草地处于健康状态,围栏外的温性荒漠类草地为亚健康状态。通过构建新疆草地生态系统健康评价体系,能够为基层草原部门开展草地生态健康评价提供参考,促进草地可持续发展。

submitted time 2022-01-26 Cooperative journals:《干旱区研究》 Hits2462Downloads310 Comment 0

8. chinaXiv:202201.00064 [pdf]

Determination of neutron-skin thickness using configurational information entropy

Ma, Chun-Wang ; Liu, Yi-Pu; Wei, Hui-Ling; Pu, Jie; Cheng, Kai-Xuan; Wang, Yu-Ting
Subjects: Physics >> Nuclear Physics

Configurational information entropy (CIE) theory was employed to determine the neutron skin thickness of neutron-rich calcium isotopes. The nuclear density distributions and fragment cross-sections in 350 MeV/u 40-60Ca + 9Be projectile fragmentation reactions were calculated using a modified statistical abrasion-ablation model. CIE quantities were determined from the nuclear density, isotopic, mass, and charge distributions. The linear correlations between the CIE determined using the isotopic, mass, and charge distributions and the neutron skin thickness of the projectile nucleus show that CIE provides new methods to extract the neutron skin thickness of neutron-rich nuclei.

submitted time 2022-01-21 Cooperative journals:《Nuclear Science and Techniques》 Hits3728Downloads388 Comment 0

9. chinaXiv:202201.00065 [pdf]

Anisotropy flows in Pb–Pb collisions at LHC energies from parton scatterings with heavy quark trigger

Wang, Hai; Chen, Jin-Hui
Subjects: Physics >> Nuclear Physics

By implementing an additional heavy quark–antiquark pair production trigger in a multiphase transport (AMPT) model, we study the effect on anisotropy flows of identified particles with a focus on charged particles and quarkonium (J/Ψ and Υ). A systematic increase in the collision rate for active partons in the AMPT model with such an implementation has been observed. It leads to a slight increase of identified particles anisotropy flows as a function of transverse momentum (pT ) and rapidity, and gives a better description of the experimental data of elliptic flow toward larger pT . Our approach provides an efficient way to study the heavy quark dynamics in the AMPT model at LHC energies.

submitted time 2022-01-21 Cooperative journals:《Nuclear Science and Techniques》 Hits3568Downloads339 Comment 0

10. chinaXiv:202201.00035 [pdf]

基于氘核碎裂的高能中子束的产生机制的研究

Wang, Rensheng; Ou, Li; Xiao, Zhigang
Subjects: Physics >> Nuclear Physics

在改进的量子分子动力学模型框架下,研究了高能氘核在重靶核作用下的碎裂过程,尤其近零度角产生的中子。模拟重现了 102 MeV d+C 反应中实验测量的中子双微分截面。根据模型与实验结果的一致性,论证了通过氘核在碳靶上碎裂而产生高能中子束的可行性。但因氘核内部核子的费米运动,使得包含实验室0°在内的中子能量具有相当大的能量展宽。基于模型计算,通过测量氘核碎裂过程中出射的伴随质子,出射中子能量可约束在5%(1σ)以内。进一步,本工作论证了基于伴随质子测量的单能高能中子束产生的可行性。

submitted time 2022-01-07 Hits6024Downloads481 Comment 0

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