Abstract
Total energy local density calculations of the effects of pressure on the HgBa2Can-1CunO2n+2+δ (n = 1,2,3) superconductors show that the compressibility is anisotropic. Estimates of the bond compressibilities show that the Cu-O(2) (apical) bond is extremely compressible, while the Hg-O(2) bond is the least compressible. A simple model is proposed to describe compressibilities of Hg-1212, Hg-1223 and Hg-1234 on the basis of results obtained for the infinite layer (Sr1-xCax)1-yCuO2 and Hg-1201 compounds. The energy location of the van Hove singularity (vHs) - important in several theories of high-Tc superconductivity - is found to move towards EF with pressure, thereby showing a correspondence between the number of holes (from dopants) needed to shift EF down to the vHs and the pressure needed to be applied to a fixed dopant material to achieve the best Tc. Some consequences for understanding the pressure effects on the Tc of the Hg superconductors and possible experiments are suggested.
Original language | English (US) |
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Pages (from-to) | 38-46 |
Number of pages | 9 |
Journal | Physica C: Superconductivity and its applications |
Volume | 222 |
Issue number | 1-2 |
DOIs | |
State | Published - Mar 10 1994 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering