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Compressed H₃S: Fits to the Empirical H_c2(T) Data and a Discussion of the meissner effect

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World Journal of Condensed Matter Physics 2023年第4期13卷 111-127页

作者： Gulshan Prakash Malik Vijaya Shankar Varma Gurugram India Theory Group School of Environmental Sciences Jawaharlal Nehru University New Delhi India Department of Physics and Astrophysics University of Delhi Delhi India

Based on μ-, T- and H-dependent pairing and number equations and the premise that μ(T) is predominantly the cause of the variation of the upper critical field Hc2(T), where μ, T and H denote the chemical potential, temperature and the applied field, respectively, we provide in this paper fits to the empirical Hc2(T) data of H3S reported by Mozaffari, et al. (2019) and deal with the issue of whether or not H3S exhibits the meissner effect. Employing a variant of the template given by Dogan and Cohen (2021), we examine in detail the results of Hirsch and Marsiglio (2022) who have claimed that H3S does not exhibit the meissner effect and Minkov, et al. (2023) who have claimed that it does. We are thus led to suggest that monitoring the chemical potential (equivalently, the number density of Cooper pairs Ns at T = Tc) should shed new light on the issue being addressed.

关键词： Compressed H3S Upper and Lower Critical Fields Chemical Potential Generalized Pairing and Number Equations Coherence Length Penetration Depth meissner effect

Levitation and lateral forces between a point magnetic dipole and a superconducting sphere

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Chinese Physics B 2016年第5期25卷 453-456页

作者： H M Al-Khateeb M K Alqadi F Y Alzoubi B Albiss M K Hasan (Qaseer) N Y Ayoub Department of Physics Jordan University of Science and Technology School of Basic Sciences and Humanities German Jordanian University

The dipole–dipole interaction model is employed to investigate the angular dependence of the levitation and lateral forces acting on a small magnet in an anti-symmetric magnet/superconducting sphere system. Breaking the symmetry of the system enables us to study the lateral force which is important in the stability of the magnet above a superconducting sphere in the meissner state. Under the assumption that the lateral displacement of the magnet is small compared to the physical dimensions of our proposed system, analytical expressions are obtained for the levitation and lateral forces as a function of the geometrical parameters of the superconductor as well as the height, the lateral displacement, and the orientation of the magnetic moment of the magnet. The dependence of the levitation force on the height of the levitating magnet is similar to that in the symmetric magnet/superconducting sphere system within the range of proposed lateral displacements. It is found that the levitation force is linearly dependent on the lateral displacement whereas the lateral force is independent of this displacement. A sinusoidal variation of both forces as a function of the polar and azimuthal angles specifying the orientation of the magnetic moment is observed. The relationship between the stability and the orientation of the magnetic moment is discussed for different orientations.

关键词： lateral and levitation forces meissner effect dipole–dipole interaction model superconductor

Generalized Drude model and electromagnetic screening in metals and superconductors

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Chinese Physics B 2018年第5期27卷 453-457页

作者：王达 National Laboratory of Solid State Microstructures & School of Physics Nanjing University

Electromagnetic screening is studied from the perspective of fluid mechanics by generalizing the Drude theory, which unifies three known results： Thomas–Fermi screening of the longitudinal field in both metals and superconductors, the skin effect of the transverse field in metals, and the meissner effect in superconductors. In the special case of superfluid electrons, we slightly generalize the London equations to incorporate the longitudinal electric fields. Moreover, regarding the experiments, our study points out that the dynamical measurement may overestimate the superfluid density.

关键词： electromagnetic screening Thomas-Fermi screening London penetration depth meissner effect

The Magnetic Penetration Depth Calculated with the Mechanism of “Close-Shell Inversion”

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Journal of Materials Science and Chemical Engineering 2023年第12期11卷 64-75页

作者： Wangzuo Shangguan Xusheng Wang Ziqian Huang School of Pharmacy Guangxi University of Chinese Medicine Nanning China School of Electrical and Electronic Engineering Nanyang Technological University Singapore City Singapore

meissner effect is one of the two fundamental properties of superconductors, it allows them to actively exclude external magnetic fields from their interior, leaving the field to decay quickly from the surface to the interior within a very thin layer whose thickness is characterized by the penetration depth . Based on the mechanism of “close-shell inversion” for superconductivity proposed earlier, we proceed in this paper to calculate the magnetic penetration depth. It is found that repelling the external magnetic field is just a spontaneous and dynamic response of conduction electrons in superconductors. Calculation results show that the net magnetic field decays exponentially, in consistent with the existing theories and experimental data. .

关键词： meissner effect Magnetic Penetration Depth

The Formation of the Electronic Tornado is the Basis of Superconductivity

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Journal of Computer Science Research 2021年第1期3卷 44-54页

作者： Binggong Chang Suny New YorkUSA

The space-time ladder theory reveals that the formation of electronic tornadoes,or the formation of electronic dissipative structures,to be precise,the enhancement of electronic Energy Qi field is the basis of superconductivity.The surrounding area of the electronic tornado is expanding,which is the basis of the meissner effect,and the center is contracting,which is the basis of the pinning force.When the attractive force of the Energy Qi field is greater than the Coulomb repulsive force,the electrons form a Cooper pair and release dark energy into virtual space-time.When the dark energy increases to a certain extent,the virtual space-time frees the Cooper pair and forms an electron-virtual space-time wave,which fluctuates freely in the superconducting material,which is the basis for the superconducting resistance to be zero.This is similar to the principle of a hot air balloon.The virtual space-time is hot air and the electron pair is a hot air balloon device.Conductor electrons are free and easy to emit dark energy,resulting in insufficient dark energy,and it is not easy to form electron-pair virtual space-time waves,so the superconducting critical temperature is very low.This is because the emission coefficient of the conductor is too high.Insulator electrons are not easy to emit dark energy and easily form electron-pair virtual space-time waves.Therefore,the superconducting critical temperature is slightly higher because of the low emission coefficient of the insulator.The solution of the Qi-space-time wave equation,that is,the coherence coefficient,is an important factor in superconductivity.In addition,the conditions under which tornadoes form are also an important basis for superconductivity.Finally,it is emphasized that the coherence coefficient and prevention of dark energy emission are the two most important elements for preparing superconducting materials.

关键词： Superconductivity Electronic tornado Zero resistance meissner effect Josephson effect Cooper pair virtual space-time wave Energy Qi field force Coherence coefficient