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Cu valency change induced by O doping in YBCPO
W M Temmerman1, H Winter, Z Szotek
1Daresbury Laboratory, Cheshire, United Kingdom.
Physical Review Letters
|April 6, 2001
Summary
This study investigates YBa2Cu3O6, YBa2Cu3O6.5, and YBa2Cu3O7 using ab initio local spin density. It reveals how oxygenation drives the CuO2 plane from insulating to metallic by delocalizing electron bands.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Computational Chemistry
Background:
- YBa2Cu3Ox (YBCO) is a crucial high-temperature superconductor.
- Understanding its electronic structure is key to elucidating superconductivity mechanisms.
- Oxygen stoichiometry significantly impacts YBCO's properties.
Purpose of the Study:
- To investigate the electronic structure and magnetic properties of YBa2Cu3O6, YBa2Cu3O6.5, and YBa2Cu3O7.
- To understand the role of copper (Cu) valency and electron delocalization in the transition from insulating to metallic states.
- To provide insights into the fundamental physics governing YBCO's behavior.
Main Methods:
- Ab initio local spin density approximation (LSDA) calculations.
- Inclusion of self-interaction corrections (SIC) for Cu d-states.
- Analysis of electronic band structure and charge density.
Main Results:
- Accurate description of antiferromagnetic and insulating state in YBa2Cu3O6 with specific Cu valencies.
- Demonstration of the transition from insulating to metallic behavior in the CuO2 plane upon oxygenation.
- Identification of the delocalization of the Cu d(x2-y2)-O2 p(x)-O3 p(y) band as the key mechanism for metallicity.
Conclusions:
- The study provides a detailed ab initio understanding of YBCO's electronic and magnetic properties.
- Self-interaction corrections are essential for accurately describing Cu valency and electronic transitions.
- Oxygenation-induced electronic delocalization is fundamental to the transition to metallic behavior in YBCO.