Showing papers on "High-temperature superconductivity published in 1972"
TL;DR: A new system of high-temperature superconductors is reported, where A is Cu, Zn, Mg, Ag, Cd, Sn, or Pb, and the compounds are rhombohedral with transition temperatures ranging from ∼ 2.5�K for the Cd compound to ∼ 13�Kfor the Pb compound.
Abstract: A new system of high-temperature superconductors is reported. The compounds, Mo6 - xAxS6 where A is Cu, Zn, Mg, Ag, Cd, Sn, or Pb, are rhombohedral with a ≃6.5 angstroms and ∼90°. The transition temperatures range from ∼ 2.5°K for the Cd compound to ∼ 13°K for the Pb compound.
197 citations
TL;DR: In this article, the existence of impurity bands in superconductors with magnetic impurities is discussed and discussed how their existence is related to the Kondo effect, and it is shown how impurity band existence can be inferred from magnetic impurity.
58 citations
TL;DR: In this article, a brief review of the present situation in theoretical investigations of high temperature superconductivity is presented, where the main subject is a discussion of the formula for a critical temperature T c for a homogeneous and isotropic substance with arbitrary permeability ϵ ( q, ω ).
33 citations
TL;DR: In this paper, the exciton mechanism of superconductivity has been investigated for the production of high temperature superconductors, for which the critical temperature T c would reach hundreds of degrees, or at least liquid air temperature.
Abstract: The critical temperature, T c, for all presently known superconductors does not exceed 20°K. This fact obviously limits the range of applications of superconductivity in technology in a very fundamental way. On the whole, the reason why the value of T c for ‘ordinary’ superconductors should not exceed 20–40 °K is fairly well understood on the basis of the existing theory of superconductivity. At the same time, there apparently could exist high temperature superconductors for which the temperature T c would reach hundreds of degrees, or at least liquid air temperature. Possible means of producing high temperature superconductors are considered in this article. Special attention is paid to what can be called the exciton mechanism of superconductivity.
24 citations
TL;DR: In this paper, the upper critical fields of several Nb x Ga 1-x alloys with values of T c from 13.3 K to 20.2 K have been measured at temperatures from 4.2 to 4.4 K with dc and pulsed magnet fields.
23 citations
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12 citations
TL;DR: In this paper, Eliashberg's theory is extended to type-II superconductors in such a way that band structure effects and anisotropies of the phonon-induced electron-electron interaction are included.
7 citations
TL;DR: In this paper, the magnetic properties of type-II superconductors can be computed from a knowledge of the boson characteristic function which can be determined from experimental data for the scattering of neutrons by a vortex lattice.
6 citations
TL;DR: In this paper, the influence of Fermi-surface topology changes on the transition temperature and critical impurity concentration of superconductors with paramagnetic impurities was investigated.
TL;DR: In this article, it was shown that superconductivity only occurs if valency electrons of a band can move in at least one space direction without intersecting any nodal surfaces.
Abstract: Abstract By consideration of superconducting compounds, whose chemical bond nature is known or can be derived with some certainty, it is shown that superconductivity only occurs, if valency electrons of a band can move in at least one space direction without intersecting any nodal surfaces. This applies both for metallic substances and for semiconductors. The following examples are discussed: 1. Metallic and semiconducting compounds composed of elements of the main groups and having a lattice similar to that of NaCl. 2. Nb- and Ta-chalcogenides with MoS2-structure. 3. The clathrate-compound [Ag7O8]+X-. 4. LaC2 with CaC2-structure. 5. Metallic and semiconducting perovskites. 6. Spinels and interstitial compounds with NaCl-structure. 7. Pyrites. 8. Some metals and their alloys. In the case of s-electrons, this condition is fulfilled for all space directions, in the case of <5-bonds only along the intersecting line of the two nodal planes. A “δ”-bond is often - especially in an NaCl-type lattice - associated with a translation perpendicular to this intersecting line (in the NaCl-type lattice a translation by a/2) and a rotation by 90°. In such a “δt”-bond system the four segments of a dt2g-electron belong to four adjacent canals of quadratic cross-section (in the NaCl-type lattice the side length is a/2) which are not intersected by nodal surfaces. Only electrons fulfilling the condition indicated above can be considered as “free electrons”.
Journal Article•
TL;DR: In the search for high-temperature superconductors, the path led from individual elements to binary compounds, to pseudobinary compounds, and eventually to ternary compounds as mentioned in this paper.
Abstract: In the search for high‐temperature superconductors the path led from individual elements to binary compounds, to pseudobinary compounds, and eventually to ternary compounds. At first at least one of the elements in the binary compound was superconducting. Eventually hundreds of binary compounds were found in which neither of the elements was superconducting above 1 K.