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Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures
Published on: October 9, 2012
Photoemission from buried interfaces in SrTiO3/LaTiO3 superlattices
M Takizawa1, H Wadati, K Tanaka
1Department of Physics and Department of Complexity Science and Engineering, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwashi, Chiba 277-8561, Japan.
Physical Review Letters
|October 10, 2006
Summary
Electronic reconstruction occurs at strontium titanate/lanthanum titanate superlattices. Annealing enhances charge spread, boosting coherent spectral weight at the interface, as confirmed by dynamical-mean-field theory calculations.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Surface Science
Background:
- Strontium titanate (SrTiO3) is a band insulator, while lanthanum titanate (LaTiO3) is a Mott insulator.
- Interfaces between such materials can exhibit novel electronic properties due to charge transfer and reconstruction.
Purpose of the Study:
- To investigate the electronic properties of SrTiO3/LaTiO3 superlattices with varying SrTiO3 layer thickness.
- To understand the phenomenon of electronic reconstruction at the interface.
- To explore the impact of annealing on interface properties.
Main Methods:
- Photoemission spectroscopy was used to measure the electronic spectra.
- SrTiO3/LaTiO3 superlattices with a variable topmost SrTiO3 layer were fabricated.
- Layer dynamical-mean-field-theory (DMFT) calculations were performed for comparison.
Main Results:
- A finite coherent spectral weight and Fermi cutoff were observed at chemically abrupt SrTiO3/LaTiO3 interfaces.
- Annealing at high temperatures (approx. 1000°C) led to Sr/La interdiffusion.
- Annealing reduced the incoherent spectral weight and enhanced the coherent part due to charge spread.
Conclusions:
- An electronic reconstruction occurs at the SrTiO3/LaTiO3 interface.
- Annealing-induced interdiffusion significantly modifies the electronic structure by spreading charge.
- Experimental findings are consistent with layer dynamical-mean-field-theory predictions.
