Axial oxygen-centered lattice instabilities and high-temperature superconductivity
Science (New York, N.Y.)
|June 15, 1990
Summary
High-temperature superconductivity in YBa(2)Cu(3)O(7) and T1Ba(2)Ca(3)Cu(4)O(11) involves a pseudo-(anti)ferroelectric lattice instability. This ionic motion couples with phonon and electronic channels for superconductivity.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid State Chemistry
Background:
- Superconductivity in cuprates like YBa(2)Cu(3)O(7) and T1Ba(2)Ca(3)Cu(4)O(11) is a key area of research.
- Understanding the mechanisms behind high-temperature superconductivity is crucial for technological advancements.
Purpose of the Study:
- To investigate the lattice dynamics associated with the superconducting transition in YBa(2)Cu(3)O(7) and T1Ba(2)Ca(3)Cu(4)O(11).
- To explore the relationship between lattice instability, oxygen content, and metal substitution in these materials.
- To propose a scenario for high-temperature superconductivity involving coupled phonon and electronic interactions.
Main Methods:
- Copper K-edge x-ray absorption spectroscopy was used to probe lattice behavior.
- Analysis focused on axial oxygen-centered lattice instabilities and their potential well characteristics.
- Investigated the effects of reduced oxygen content and cobalt substitution for copper.
Main Results:
- A pseudo-(anti)ferroelectric lattice instability was identified at the superconducting transition in YBa(2)Cu(3)O(7) (93 K) and T1Ba(2)Ca(3)Cu(4)O(11) (~120 K).
- This instability involves the softening of a double potential well, reducing copper-oxygen distances and barrier height near the transition.
- The mean square relative displacement of axial oxygen in YBa(2)Cu(3)O(7) is sensitive to oxygen content and cobalt substitution.
Conclusions:
- The observed lattice instability is coupled to the superconducting transition, suggesting its role in the phenomenon.
- A model for high-temperature superconductivity is proposed, highlighting the synergistic involvement of phonon and electronic (charge transfer) channels.
- The findings provide insights into the complex interplay of lattice dynamics and electronic properties in cuprate superconductors.
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