When we place a superconductor above a magnet, we observe a levitation of the superconductor above the magnet. But when placing a perfect diamagnetic material above a magnet, no levitation is observed. This difference...When we place a superconductor above a magnet, we observe a levitation of the superconductor above the magnet. But when placing a perfect diamagnetic material above a magnet, no levitation is observed. This difference in behavior between the superconductor and the perfect diamagnetic in the presence of an external magnetic field is explained by the classical description of the Meissner effect implemented in this article. We have shown here that the Meissner effect is nothing more than an electromagnetic interaction between the magnetic field created by the superconductor and the magnetic field of the magnet. This classical description of the Meissner effect also allowed us to give a more realistic explanation of the expansion of the universe. We have shown that this expansion is a phenomenon that simply results from a Meissner effect between superconducting dark matter and the magnetic fields of stars. We also pointed out that this expansion is accelerated because the gravitational force between dark matter and the stars around it decreases as these stars move away from the superconducting dark matter. We also used this classical description of the Meissner effect to propose a new method of remote sensing in space in which the superconducting satellite is in perpetual levitation on the night side of the earth and a new and more efficient way to discover new particles through a superconducting detector levitating in the upper atmosphere.展开更多
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 H<sub>c</sub><sub>2</sub>(T), wh...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 H<sub>c</sub><sub>2</sub>(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 H<sub>c</sub><sub>2</sub>(T) data of H<sub>3</sub>S reported by Mozaffari, et al. (2019) and deal with the issue of whether or not H<sub>3</sub>S 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 H<sub>3</sub>S 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 N<sub>s</sub> at T = T<sub>c</sub>) should shed new light on the issue being addressed.展开更多
The paramagnetic Meissner effect (PME) was observed on the field-cooled M-T curves of melt-textured Y0.99Nd0.01Ba2Cu3O7-y in applied magnetic fields from 1kOe to 40kOe. In the magnetic field below 1kOe, the sample und...The paramagnetic Meissner effect (PME) was observed on the field-cooled M-T curves of melt-textured Y0.99Nd0.01Ba2Cu3O7-y in applied magnetic fields from 1kOe to 40kOe. In the magnetic field below 1kOe, the sample undergoes the typical transition from the normal state to the superconducting state when it was cooled down. The applied magnetic fields in which the PME occurs, are very high compared with the fields reported in literatures. We propose that the occurrence of the PME may be due to a phase transition of flux vortices in the superconductors.展开更多
As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation which is not the result of an attractive electron-electron interaction but can be described in terms of ...As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation which is not the result of an attractive electron-electron interaction but can be described in terms of quantum mechanical constraining forces. This mechanism operates in narrow, roughly half-filled superconducting bands of special symmetry and is evidently responsible for the formation of Cooper pairs in all superconductors. Here we consider this new mechanism within an outer magnetic field. We show that in the magnetic field the constraining forces produce Cooper pairs of non-vanishing total momentum with the consequence that an electric current flows within the superconductor. This current satisfies the London equations and, consequently, leads to the Meissner effect. This theoretical result is confirmed by the experimental observation that all superconductors, whether conventional or unconventional, exhibit the Meissner effect.展开更多
The electromagnetic waves are considered in this article as the mediators of interaction in the Meissner Effect or the diamagnetic property of the superconductors. During the cooling of a superconductor electromagneti...The electromagnetic waves are considered in this article as the mediators of interaction in the Meissner Effect or the diamagnetic property of the superconductors. During the cooling of a superconductor electromagnetic waves may be released when the electrons occupy lower states of the energy. These electromagnetic waves may combine in circularly, elliptically and spherically rotating way, being called in this article the rounded electromagnetic fields. The application of the Lorentz transformation of the Special Theory of Relativity to the magnetic vectors of the mediating electromagnetic fields implies the magnetic orthogoniopedic effect inside the bulk of a superconductor in the Meissner Effect.展开更多
We report the Meissner effect studies on an Fe Se thin film grown on Nb-doped Sr Ti O3 substrate by molecular beam epitaxy. Two-coil mutual inductance measurement clearly demonstrates the onset of diamagnetic screenin...We report the Meissner effect studies on an Fe Se thin film grown on Nb-doped Sr Ti O3 substrate by molecular beam epitaxy. Two-coil mutual inductance measurement clearly demonstrates the onset of diamagnetic screening at 65 K, which is consistent with the gap opening temperature determined by previous angle-resolved photoemission spectroscopy results. The applied magnetic field causes a broadening of the superconducting transition near the onset temperature, which is the typical behavior for quasi-two-dimensional superconductors. Our results provide direct evidence that Fe Se thin film grown on Nb-doped Sr Ti O3 substrate has an onset TC* 65 K,which is the highest among all iron-based superconductors discovered so far.展开更多
Theoretical and experimental results show that the state of minimum Ginsburg Landau free energy of small superconducting particles contains no flux line if the applied field is smaller than its critical field. For suc...Theoretical and experimental results show that the state of minimum Ginsburg Landau free energy of small superconducting particles contains no flux line if the applied field is smaller than its critical field. For such micron sized particles, after being cooled in a small magnetic field (e.g. less than 100 μT), the moment remaining during subsequent zero field warming contains almost no contribution from trapped flux and is dominated entirely by the paramagnetic Meissner effect (PME) of the particles. A systematic study of such a moment has been carried out to reveal its characteristic behavior of temperature, magnetic field and cooling or warming rate dependence. Methods for removing and recovering the PME of small superconducting particles are also reported.展开更多
A range of powdered Bi:2 212 samples exhibiting the paramagnetic Meissner effect (PME) are systematically examined. Interpretation of the results is made in terms of a phenomenological model in which there is a concen...A range of powdered Bi:2 212 samples exhibiting the paramagnetic Meissner effect (PME) are systematically examined. Interpretation of the results is made in terms of a phenomenological model in which there is a concentration within the material of small local moments that can be polarized during a field cooling. Information about the magnitudes of these local m0oments and their distribution are deduced. Relations between the local moments and the particle sizes, the weak link, oxygen content and the interactions between the local moments are also discussed. Comparison of the results from small particles and bulk samples shows that conclusions obtained from small particle experiments are reliable and universal.展开更多
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 ...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. .展开更多
基于商用电磁场有限元软件以及M e issner效应假设,提出了对由块状高温超导体和永磁体组成的高温超导推力轴承静态特性进行分析的方法,分析了永磁体的结构对高温超导推力轴承悬浮力的影响。结果发现:永磁体的结构及磁极排列方式对高温...基于商用电磁场有限元软件以及M e issner效应假设,提出了对由块状高温超导体和永磁体组成的高温超导推力轴承静态特性进行分析的方法,分析了永磁体的结构对高温超导推力轴承悬浮力的影响。结果发现:永磁体的结构及磁极排列方式对高温超导推力轴承悬浮力的影响很大,适当地选择永磁体的结构和磁极排列方式可以显著地提高高温超导推力轴承的悬浮力。展开更多
文摘When we place a superconductor above a magnet, we observe a levitation of the superconductor above the magnet. But when placing a perfect diamagnetic material above a magnet, no levitation is observed. This difference in behavior between the superconductor and the perfect diamagnetic in the presence of an external magnetic field is explained by the classical description of the Meissner effect implemented in this article. We have shown here that the Meissner effect is nothing more than an electromagnetic interaction between the magnetic field created by the superconductor and the magnetic field of the magnet. This classical description of the Meissner effect also allowed us to give a more realistic explanation of the expansion of the universe. We have shown that this expansion is a phenomenon that simply results from a Meissner effect between superconducting dark matter and the magnetic fields of stars. We also pointed out that this expansion is accelerated because the gravitational force between dark matter and the stars around it decreases as these stars move away from the superconducting dark matter. We also used this classical description of the Meissner effect to propose a new method of remote sensing in space in which the superconducting satellite is in perpetual levitation on the night side of the earth and a new and more efficient way to discover new particles through a superconducting detector levitating in the upper atmosphere.
文摘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 H<sub>c</sub><sub>2</sub>(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 H<sub>c</sub><sub>2</sub>(T) data of H<sub>3</sub>S reported by Mozaffari, et al. (2019) and deal with the issue of whether or not H<sub>3</sub>S 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 H<sub>3</sub>S 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 N<sub>s</sub> at T = T<sub>c</sub>) should shed new light on the issue being addressed.
基金the National R&D Center on Superconductivity of China and was carried out within the scientific exchange program between China and the Netherlands.
文摘The paramagnetic Meissner effect (PME) was observed on the field-cooled M-T curves of melt-textured Y0.99Nd0.01Ba2Cu3O7-y in applied magnetic fields from 1kOe to 40kOe. In the magnetic field below 1kOe, the sample undergoes the typical transition from the normal state to the superconducting state when it was cooled down. The applied magnetic fields in which the PME occurs, are very high compared with the fields reported in literatures. We propose that the occurrence of the PME may be due to a phase transition of flux vortices in the superconductors.
文摘As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation which is not the result of an attractive electron-electron interaction but can be described in terms of quantum mechanical constraining forces. This mechanism operates in narrow, roughly half-filled superconducting bands of special symmetry and is evidently responsible for the formation of Cooper pairs in all superconductors. Here we consider this new mechanism within an outer magnetic field. We show that in the magnetic field the constraining forces produce Cooper pairs of non-vanishing total momentum with the consequence that an electric current flows within the superconductor. This current satisfies the London equations and, consequently, leads to the Meissner effect. This theoretical result is confirmed by the experimental observation that all superconductors, whether conventional or unconventional, exhibit the Meissner effect.
文摘The electromagnetic waves are considered in this article as the mediators of interaction in the Meissner Effect or the diamagnetic property of the superconductors. During the cooling of a superconductor electromagnetic waves may be released when the electrons occupy lower states of the energy. These electromagnetic waves may combine in circularly, elliptically and spherically rotating way, being called in this article the rounded electromagnetic fields. The application of the Lorentz transformation of the Special Theory of Relativity to the magnetic vectors of the mediating electromagnetic fields implies the magnetic orthogoniopedic effect inside the bulk of a superconductor in the Meissner Effect.
基金supported by the National Natural Science Foundation and Ministry of Science and Technology of China(2015CB921000 and 2012CB921402)Yihua Wang is partially supported by the Urbanek Fellowship of the Department of Applied Physics at Stanford UniversityK.A.Moler is supported by the Department of Energy,Office of Science,Basic Energy Sciences,Materials Sciences and Engineering Division,under Contract DEAC02-76SF00515
文摘We report the Meissner effect studies on an Fe Se thin film grown on Nb-doped Sr Ti O3 substrate by molecular beam epitaxy. Two-coil mutual inductance measurement clearly demonstrates the onset of diamagnetic screening at 65 K, which is consistent with the gap opening temperature determined by previous angle-resolved photoemission spectroscopy results. The applied magnetic field causes a broadening of the superconducting transition near the onset temperature, which is the typical behavior for quasi-two-dimensional superconductors. Our results provide direct evidence that Fe Se thin film grown on Nb-doped Sr Ti O3 substrate has an onset TC* 65 K,which is the highest among all iron-based superconductors discovered so far.
文摘Theoretical and experimental results show that the state of minimum Ginsburg Landau free energy of small superconducting particles contains no flux line if the applied field is smaller than its critical field. For such micron sized particles, after being cooled in a small magnetic field (e.g. less than 100 μT), the moment remaining during subsequent zero field warming contains almost no contribution from trapped flux and is dominated entirely by the paramagnetic Meissner effect (PME) of the particles. A systematic study of such a moment has been carried out to reveal its characteristic behavior of temperature, magnetic field and cooling or warming rate dependence. Methods for removing and recovering the PME of small superconducting particles are also reported.
文摘A range of powdered Bi:2 212 samples exhibiting the paramagnetic Meissner effect (PME) are systematically examined. Interpretation of the results is made in terms of a phenomenological model in which there is a concentration within the material of small local moments that can be polarized during a field cooling. Information about the magnitudes of these local m0oments and their distribution are deduced. Relations between the local moments and the particle sizes, the weak link, oxygen content and the interactions between the local moments are also discussed. Comparison of the results from small particles and bulk samples shows that conclusions obtained from small particle experiments are reliable and universal.
文摘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. .
文摘基于商用电磁场有限元软件以及M e issner效应假设,提出了对由块状高温超导体和永磁体组成的高温超导推力轴承静态特性进行分析的方法,分析了永磁体的结构对高温超导推力轴承悬浮力的影响。结果发现:永磁体的结构及磁极排列方式对高温超导推力轴承悬浮力的影响很大,适当地选择永磁体的结构和磁极排列方式可以显著地提高高温超导推力轴承的悬浮力。
