Der gegenwärtige Stand der Theorie der Supraleitung

Ginsburg, W. L.; Vogel, H.

doi:10.1002/prop.19530010302

Cited by 42 publications

(3 citation statements)

References 76 publications

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“…The mean inner potential is known to be proportional to the diamagnetic susceptibility, and the diamagnetic susceptibility increases dramatically in the superconducting state. The mean inner potential is proportional to the “size” of the atoms, and a superconductor can be understood (in some sense) as a “giant atom”, as remarked by many early workers in the field of superconductivity , as well as indicated by the fact that a superconductor has macroscopic phase coherence. As pointed out by Slater and other early workers , the giant diamagnetism of superconductors can be understood if the electronic orbits in the superconducting state are of the order of 137 lattice spacings, and the mean inner potential is proportional to the size of electronic orbits.…”

Section: Summary and Discussionmentioning

confidence: 99%

Superconductivity, diamagnetism, and the mean inner potential of solids

Hirsch

2013

Annalen der Physik

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The mean inner potential of a solid is known to be proportional to its diamagnetic susceptibility. Superconductors exhibit giant diamagnetism. What does this say about the connection between superconductivity and mean inner potential? Nothing, according to the conventional theory of superconductivity. Instead, we propose that a deep connection exists between the mean inner potential, diamagnetism, and superconductivity: that they are all intimately linked to the fundamental charge asymmetry of matter. We discuss how this physics can be probed experimentally and what the implications of different experimental findings would be for the understanding of superconductivity.Comment: Small changes in response to referee's comments. To be published in Annalen der Physi

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Section: Summary and Discussionmentioning

confidence: 99%

Superconductivity, diamagnetism, and the mean inner potential of solids

Hirsch

2013

Annalen der Physik

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“…In particular, we hope the reader will appreciate the remarkable qualitative similarity of figures 1-3, depicting the charge distribution in an atom, a system in the normal state and a superconductor within this model. Superconductors have been called 'giant atoms' in the early days of superconductivity for many other reasons [96][97][98]. The essential property of the atom, that it is not electron-hole symmetric because the negative electron is much lighter than the positive nucleus, manifests itself in the atom described by the dynamic Hubbard model and in the state of a macroscopic superconducting body described by the model, and is missed in the world described by particle-hole symmetric conventional Hubbard or Fröhlich models both at the atomic level and at the level of the macroscopic superconductor.…”

Section: Discussionmentioning

confidence: 99%

Dynamic Hubbard model: kinetic energy driven charge expulsion, charge inhomogeneity, hole superconductivity and Meissner effect

Hirsch¹

2013

Phys. Scr.

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Conventional Hubbard models do not take into account the fact that the wavefunction of an electron in an atomic orbital expands when a second electron occupies the orbital. Dynamic Hubbard models have been proposed to describe this physics. These models reflect the fact that electronic materials are generically not electron-hole symmetric, and they give rise to superconductivity driven by lowering of kinetic energy when the electronic energy band is almost full, with higher transition temperatures resulting when the ions are negatively charged. We show that the charge distribution in dynamic Hubbard models can be highly inhomogeneous in the presence of disorder, and that a finite system will expel negative charge from the interior to the surface, and that these tendencies are largest in the parameter regime where the models give rise to highest superconducting transition temperatures. High Tc cuprate materials exhibit charge inhomogeneity and they exhibit tunneling asymmetry, a larger tendency to emit electrons rather than holes in NIS tunnel junctions. We propose that these properties, as well as their high Tc's, are evidence that they are governed by the physics described by dynamic Hubbard models. Below the superconducting transition temperature the models considered here describe a negatively charged superfluid and positively charged quasiparticles, unlike the situation in conventional BCS superconductors where quasiparticles are charge neutral on average. We examine the temperature dependence of the superfluid and quasiparticle charges and conclude that spontaneous electric fields should be observable in the interior and in the vicinity of superconducting materials described by these models at sufficiently low temperatures. We furthermore suggest that the dynamics of the negatively charged superfluid and positively charged quasiparticles in dynamic Hubbard models can provide an explanation for the Meissner effect observed in high Tc and low Tc superconducting materials.PACS numbers:

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“…Similarly, we propose here that to understand superconductors it is essential to first understand them at the level of the Bohr atom. It should be noted that superconductors have often been characterized as "giant atoms" in the past [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

The Bohr superconductor

Hirsch

2016

EPL

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Superconductors have often been described as 'giant atoms'. The simplest description of atoms that heralded their quantum understanding was proposed by Bohr in 1913. The Bohr atom starts from some simple assumptions and deduces that the angular momentum of the electron in Bohr orbits is quantized in integer units of . This remarkable result, which does not appear to be implicit in the assumptions of the model, can be interpreted as a 'theoretical proof' of the model's validity to describe physical reality at some level. Similarly we point out here that from some simple assumptions it can be deduced that electrons in superconductors reside in mesoscopic orbits with orbital angular momentum /2. This implies that both in superconductors and in ferromagnets the long-range order results from elementary units of identical angular momentum. Similarly to the case of the Bohr atom we propose that this remarkable result is compelling evidence that this physics, which is not part of conventional BCS theory, describes physical reality at some level and heralds a qualitatively new understanding of superconductors.

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Der gegenwärtige Stand der Theorie der Supraleitung

Cited by 42 publications

References 76 publications

Superconductivity, diamagnetism, and the mean inner potential of solids

Superconductivity, diamagnetism, and the mean inner potential of solids

Dynamic Hubbard model: kinetic energy driven charge expulsion, charge inhomogeneity, hole superconductivity and Meissner effect

The Bohr superconductor

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