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1. chinaXiv:202206.00194 [pdf]

采用自旋转移力矩效应增强或抑制微波磁损耗

韩满贵
Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties

基于微磁学模拟结果,发现由于单根纳米线两端处磁矩矢量方向与极化电流密度()方向的不一致,导致电子的自旋转移力矩(STT)只能作用于纳米线两端的磁矩。通过提高极化电流的自旋极化率(P),这个简化模型的微波磁谱中处在18 GHz的微波磁损耗可以得到明显的抑制,同时发现与微波损耗对应的自然共振频率大小却不受STT影响。在STT效应作用下,负的磁导率虚部也是可实现的。另外,模拟结果表明通过提高STT效应中非绝热效应项中的β值,18GHz处的微波磁损耗可以得到显著的增强。基于STT效应中不同力矩的来源对磁化强度进动过程的有效阻尼常数(ɑe)的影响,上述的结果可以得到合理的解释:绝热力矩能降低ɑe数值,因而能抑制微波磁损耗的大小;非绝热力矩能提高ɑe数值,因而能增强微波磁损耗。我们的研究结果展示了一个创新性的、能主动地调控微波磁损耗的方法。

submitted time 2022-06-29 Hits10Downloads2 Comment 0

2. chinaXiv:202206.00167 [pdf]

The usage of WeChat to promote academic publishing in China A case study on Chinese Laser Press

Xiaofeng Wang; Ying Deng; Xuan Lyu; Xinlei Zhang; Lei Yang
Comment:WANG X, DENG Y, LV X, et al. The usage of WeChat to promote academic publishing in China: A case study on Chinese Laser Press [J]. Learned Publishing, 2020, 33(2): 187-91.
Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology
Subjects: Management Science >> Science ology and Management

• WeChat is one of the most popular social media applications in China and is widely used by publishers to promote their journals and activities.
• The Chinese Laser Press (CLP) has four WeChat accounts; approximately 1 million reads were recorded in 2018.
• The most influential WeChat account of the CLP had almost 43,000 subscribers at the end of 2019.
• WeChat is a successful tool for connecting journals with readers and can increase the visibility of the journals both within China and elsewhere.
• Connecting with researchers via WeChat is helping CLP maintain relations with researchers throughout their career.

submitted time 2022-06-23 Hits109Downloads28 Comment 0

3. chinaXiv:202101.00003 [pdf]

On dark matter

Xian-Qiao Yu
Subjects: Physics >> The Physics of Elementary Particles and Fields

In this article, I shall propose an enlightening view on the origin of dark matter abundance, in which I introduce a neutral primordial field, which is a new field beyond the standard model, the mass of the primordial field is confined in the vicinity of neutrino mass (or 1-2 orders of magnitude different from the neutrino mass). All the standard model elementary particles are produced spontaneously from this field in the Big Bang epoch of the universe and then these produced elementary particles decayed or annihilated in the well-known standard model interactions. The relic of the primordial field appears in a form of vacuum energy can not only give naturally the correct abundance of dark matter in the present universe, but provide a natural solution to the cosmological constant problem as well. We find that the conventional methods of detecting dark matter either fail or have great difficulties to detect the remaining vacuum energy of the primordial field, and how to confirm the existence of the remaining energy of the universe's original energy in experiment is still an open problem.

submitted time 2022-06-21 Hits22025Downloads1604 Comment 0

4. chinaXiv:202206.00139 [pdf]

Commissioning of Laser Electron Gamma Beamline SLEGS at SSRF

王宏伟; 范功涛; 刘龙祥; 许杭华; 沈文庆; 马余刚; Hiroaki Utsunomiya; 宋龙龙; 曹喜光; 郝子锐; 陈开杰; 金晟; 杨宇萱; 胡新荣; 李鑫祥; 匡攀
Subjects: Physics >> Nuclear Physics

Shanghai Laser Electron Gamma Source (SLEGS) is a powerful gamma source to provide MeV gamma-ray beams for nuclear science and technology. It is developed as one of the sixteen beamline stations in Phase II Project of the Shanghai Synchrotron Radiation Facility (SSRF). The slant-scattering mode is for the first time systematically employed in the laser Compton scattering (LCS) at SLEGS to produce energy-tunable quasi-monoenergetic gamma-ray beams.  SLEGS officially completed its commissioning from July to December 2021. Gamma-rays in energy range of 0.25 - 21.7 MeV with the flux of 2.1 × 104 - 1.2 × 107 photons/s and the energy spread of  2 – 15 % are produced during the test. This paper reports results of the commissioning of the SLEGS beamline.

submitted time 2022-06-13 Hits626Downloads172 Comment 0

5. chinaXiv:202206.00143 [pdf]

束团压缩

朱雄伟
Subjects: Physics >> Nuclear Physics

本文提出了束团压缩物理的产生背景,束团压缩的基本原理、种类。运用束流光学的基本理论,给出了
束团压缩的基本理论公式,论证了束团压缩的高阶限制。分析讨论了单级压缩、两级压缩中存在的设计
物理问题,总结了束团压缩设计中经常遇见的一些物理问题。关于束团压缩的束流动力学问题,给出了
束团压缩器中的粒子运动方程,以及完整的动力学方程-Vlasov方程。讨论了相干同步辐射效应和微束团
不稳定性。最后,分析了磁压缩器中的误差问题。

submitted time 2022-06-13 Hits792Downloads162 Comment 0

6. chinaXiv:202206.00123 [pdf]

任意形状的双势垒的共振隧穿

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

Quantum tunneling across double potential barriers is studied. It is rigorously proved that large barriers of arbitrary shapes can be penetrated by low-energy particles with a probability of unity, i.e., realization of resonant tunneling (RT), by simply tuning the inter-barrier spacing. The results are demonstrated by tunneling of electrons and protons across rectangular and parabolic double barriers, in which resonant and sequential tunneling are distinguished. The critical dependence of the tunneling probabilities on the barrier positions not only demonstrates again the crucial role of phase factors, but also points to the possibility of ultrahigh accuracy measurements near resonance.

submitted time 2022-06-09 Hits429Downloads234 Comment 0

7. chinaXiv:202206.00038 [pdf]

相对性原理中的基础物理

陈驰一
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics

本文研究了质点动力学的相对性原理的物理逻辑。 通过对动力学中因果关系的分析,找到了牛顿力学中存在惯性力和惯性系问题的根源,发现在牛顿第二定律的形式体系中忽略了考虑参考物的因果对应。 参考系的动力学的特性应归因于参考物。 由此,参考物和被考察对象应被置于完全平等的地位。 因此,本文介绍了一个新的不受惯性系影响、并在所有平动参考系中都能直接适用的质点动力学的新方程。 对于旋转参考系,一方面由于前面已经揭示了惯性力的性质,即作用在参考物上的经过质量比加权后的真实受力。 因此,引力的物理效应已经明确不等同于惯性力的物理效应。 另一方面,根据因果对应的精神,动力学的相对性要拓展到旋转参考系,就要确定旋转参考系的物理,进一步则必须包含确定该参考系的至少四个不共面的参考物体的动力学性质。 因此,从数学上讲,还没有办法统一构建成一个简明的公式。 正是基于这两方面基础物理的考量,本文指出当前的任何广义相对性原理都是缺乏足够依据的。而对动力学的相对性原理进行拓展的关键是保证动力学方程两边的参考物的因果对应。

submitted time 2022-06-08 Hits895Downloads355 Comment 0

8. chinaXiv:202205.00036 [pdf]

热挤压聚甲基戊烯的飞秒激光内部改性

朱广宇; 向静; 周登梅; 李鹏; 欧汉文; 陈西浩
Subjects: Materials Science >> Electronic, Optical and Magnetic Materials
Subjects: Physics >> Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics

本文研究近紫外飞秒激光脉冲在聚甲基戊烯内部刻写的应用技术。我们发现该热塑材料具有偏振敏感性的特征。首先刻写实验使用数字孔径为0.05的透镜聚焦, 通过对超连续光谱的分析,测得稳定成丝刻写的激光脉冲功率在2.2MW - 9.2MW区间内,并由此推断该种材料的非线性折射率为n2387=2×10-16cm2W-1,推算三阶susceptibility χ(3)为    1.1×10-14esu。稳定成丝加工长度在300μm-1500μm。然后,实验使用数字孔径为0.4的组合物镜聚焦刻写厚度为~700μm,栅距为5μm的布拉格光栅。通过对光栅产品的衍射效率测试,推断最大折射率的变化为~0.01,这比文献中的记录数据,提高一个数量级。实验结果证明了激光脉冲峰值强度对于诱导非线性吸收的重要性,而双光子吸收为温和可控改性的物理机制。本工作为科研人员和光学器件设计和制作提供了最新的参考。

submitted time 2022-05-08 Hits1941Downloads279 Comment 0

9. 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 Hits1953Downloads369 Comment 0

10. chinaXiv:202201.00057 [pdf]

Ladderpath Approach: How Tinkering and Reuse Enhance Complexity and Information

Liu, Yu; Di, Zengru; Gerlee, Philip
Subjects: Information Science and Systems Science >> Basic Disciplines of Information Science and Systems Science
Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology

The notion of information and complexity are important concepts in many scientific fields such as molecular biology, evolutionary theory, and exobiology. Most measures of these quantities, such as Shannon entropy and related complexity measures, are only defined for objects drawn from a statistical ensemble and cannot be computed for single objects. Based on assembly theory, we attempt to fill this gap by introducing the notion of a ladderpath which describes how an object can be decomposed into a hierarchical structure using repetitive elements. From the ladderpath two measures naturally emerge: the ladderpath-index and the order-index, which represent two axes of complexity. We show how the ladderpath approach can be applied to both strings and spatial patterns and argue that all systems that undergo evolution can be described as ladderpaths. Further, we discuss possible applications to human language and the origins of life. The ladderpath approach provides a novel characterization of the information that is contained in a single object (or a system) and could aid in our understanding of evolving systems and the origin of life in particular.

submitted time 2022-04-26 Hits6187Downloads780 Comment 0

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