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Local inversion-symmetry breaking in a bismuthate high-Tc superconductor.
S Griffitt1,2, M Spaić3, J Joe1
1School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
Nature Communications
|February 15, 2023
Summary
Researchers investigated the local structure of doped perovskite Bismuthate, Ba1-xKxBiO3. They found no evidence of disproportionation, suggesting it
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid-State Chemistry
Background:
- Bismuthate perovskites, like Barium Potassium Bismuthate (Ba1-xKxBiO3), are high-temperature superconductors.
- The superconducting mechanism in these materials remains debated, with theories involving electron-phonon coupling and structural distortions.
- Understanding the local structure is crucial for elucidating the metallic and superconducting states.
Purpose of the Study:
- To investigate the local atomic structure of Ba1-xKxBiO3.
- To determine the role of structural disproportionation in the superconductivity of bismuthates.
- To explore the implications of nanoscale structural features on electronic properties.
Main Methods:
- Diffuse x-ray scattering experiments were employed to probe local atomic arrangements.
- Monte Carlo modeling was utilized to analyze the structural data.
- The study focused on samples across the insulator-metal phase boundary.
Main Results:
- No evidence for long- or short-range bismuth valence or bond disproportionation was found.
- Polaronic effects associated with disproportionation are unlikely to be relevant for superconductivity.
- Nanoscale structural correlations breaking inversion symmetry were discovered.
Conclusions:
- Structural disproportionation is not the key factor driving superconductivity in bismuthates.
- The presence of nanoscale inversion symmetry breaking has significant implications for electronic physics.
- Bismuthates are identified as materials exhibiting hidden spin-orbit coupling and a tendency for inversion-breaking displacements.
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