Cooperative Electronic Transitions--Structural Transformations.
Abstract
Experimental and theoretical studies of the electronic properties and lattice instability of the A-15 crystal class of high temperature superconductors have been completed. Experimental investigation of the structural instability in V3Si single crystals, a prototype sample in this class, and accompanying theoretical formulation of the relevant electronic density of states N(E) has shown that the form of N(E) is very sensitive to electron lifetime. The addition of defects in the lattice causes important changes in N(E) and stabilizes the cubic phase lattice. A new band structure model has been developed for A-15 high temperature superconductors based on a group theoretical approach whose key features are in agreement with less accurate band structure calculations. Experiments demonstrate that the complications of spin-orbit coupling in the prototype A-15 compound V3Si can be neglected. Preliminary measurements of the thermal expansion in a number of crystals below 77K are complete, and the work is being extended to higher temperatures (approx 500K) to investigate the influence of a superlattice development first reported by Schmidt et al. at Bell Laboratories. Electrical resistivity studies reveal a common behavior for all technologically important A-15 materials, which we have interpreted as arising from interband electron-phonon scattering.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 28, 1976
- Accession Number
- ADA027438
Entities
People
- Samuel J. Williamson
Organizations
- New York University