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08:53
Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures
Published on: October 9, 2012
Resonant photoemission from complex cuprates and nickelates
Journal of Synchrotron Radiation
|September 1, 1995
Summary
Resonant photoemission spectroscopy reveals the electronic structure of complex cuprates and nickelates. This study examines transition metal valence states and their changes with doping in these materials.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Surface Science
Background:
- Complex oxides like cuprates and nickelates exhibit fascinating electronic properties.
- Understanding the valence states of transition metals is crucial for their applications.
- Doping significantly influences the electronic behavior of these materials.
Purpose of the Study:
- To investigate the electronic contributions to the valence band density of states in complex oxides.
- To determine the valence states of transition metal ions and how they change upon doping.
- To explore the effects of doping on core-level photoemission shifts.
Main Methods:
- Synchrotron-excited resonant photoemission spectroscopy was employed.
- Measurements were performed at rare-earth 4d --> 4f and transition-metal 3p --> 3d thresholds.
- Energy Distribution Curve (EDC) and constant-initial-state (CIS) data were analyzed.
Main Results:
- The 4f and 3d contributions to the valence band density of states were examined.
- The valence states of transition metals and their modulation upon doping were studied.
- For La(2-x)Sr(x)Ni(1-y)Fe(y)O(4+delta), a Fe valence state of >= 3.0 was inferred.
- For Bi(2)Sr(2)Ca(1-x)Y(x)Cu(2)O(8+delta), Cu valence modulation effects on the 3p resonance were observed.
Conclusions:
- Resonant photoemission is a powerful tool for probing electronic structure and valence states in complex oxides.
- Doping plays a significant role in modulating the electronic properties of cuprates and nickelates.
- The findings contribute to understanding core-level shifts in photoemission spectroscopy with doping.
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