Anisotropic compressibility and effects of pressure on the electronic structure and Tc of Hg-based superconductors

D. L. Novikov; O. N. Mryasov; A. J. Freeman

doi:10.1016/0921-4534(94)90112-0

Anisotropic compressibility and effects of pressure on the electronic structure and T_c of Hg-based superconductors

D. L. Novikov, O. N. Mryasov, A. J. Freeman

Northwestern University

Research output: Contribution to journal › Article › peer-review

40 Citations (Scopus)

Abstract

Total energy local density calculations of the effects of pressure on the HgBa₂Ca_n-1Cu_nO_2n+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 (Sr_1-xCa_x)_1-yCuO₂ and Hg-1201 compounds. The energy location of the van Hove singularity (vHs) - important in several theories of high-T_c superconductivity - is found to move towards E_F with pressure, thereby showing a correspondence between the number of holes (from dopants) needed to shift E_F down to the vHs and the pressure needed to be applied to a fixed dopant material to achieve the best T_c. Some consequences for understanding the pressure effects on the T_c of the Hg superconductors and possible experiments are suggested.

Original language	English
Pages (from-to)	38-46
Number of pages	9
Journal	Physica C: Superconductivity and its applications
Volume	222
Issue number	1-2
DOIs	https://doi.org/10.1016/0921-4534(94)90112-0
Publication status	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

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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.",

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AU - Freeman, A. J.

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N2 - 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.

AB - 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.

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