Search For New Superconductors Research Articles

Search for new superconductors by magnetosensitive microwave absorption

We used the magnetosensitive microwave absorption (MMA) effect to search for new superconductive materials. This effect is very sensitive to the superconductive phase quantity in the sample under test and can detect very small quantities of this phase up to 10 −3% of this in a sample volume. As nonsuperconductors manifest MMA effect too, it is necessary to find out the MMA peculiarities which can be attributed only to a superconductive phase. To solve the problem we considered peculiarities of MMA effect deduced experimentally in superconductors of type I, II as well as for the HTSC and compared their properties with those in the materials with magnetic dipoles and the magnetoresistive effect in semiconductors. Thus we found the main peculiarities of the MMA effect the superconductive phase and observed them in some glasses enriched with ions of Cu, Ni, Co, or Fe.

Multivalence Resonance-Condensation Model for Electron Pairing and Superconductivity in High Tc Superconductors: A Possible Novel and Universal Origin of Superconductivity

The multivalence resonance-condensation model (MVRC model) is suggested as a possible novel and universal origin of high Tc superconductivity and successfully applied to various high Tc oxide superconductors with perovskite-related structure, such as strongly anisotropic layered cuprates and almost isotropic bismuthates. The MVRC state is Bose condensation of the resonance hybrids between two kinds of multivalence states of the cations Cu1+, 2+, 3+(Bi3+, 4+, 5+, Pb2+, 3+, 4+, etc.) responsible for the superconductivity and is shown from its simple geometrical configuration on the actual crystal lattice planes to provide a unified picture of the superconducting state of all these systems in a consistent manner. Most importantly, the model reveals the inherent deep connection of superconductivity with the fundamental and universal nature of matter, i.e., the chemical bond. Thus, the model is expected to be a guiding chemical and structural principle in both the search for new superconductors and the construction of a new quantitative theoretical model.