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Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study
Surajit Saha1,2, Bing-Chen Cao3, M Motapothula1,2
1NUSNNI-NanoCore, 5A Engineering Drive 1, National University of Singapore, 117411, Singapore.
Scientific Reports
|November 16, 2016
Summary
Defect states with magnetic properties were found in rare-earth perovskites using Raman spectroscopy. These defects, likely vacancies or anti-site issues, could enable tunable magneto-optic applications.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spectroscopy
Background:
- Rare-earth based perovskite oxides exhibit interesting dielectric properties.
- Defect states can significantly influence material properties.
- Understanding defect-related magnetism is crucial for advanced applications.
Purpose of the Study:
- To investigate defect-related states with magnetic degrees of freedom in LaAlO3 and other rare-earth perovskites.
- To determine the origin of these magnetic states.
- To establish guidelines for defect engineering in perovskites for magneto-optic applications.
Main Methods:
- Inelastic light scattering (Raman spectroscopy) at low temperatures.
- Applied magnetic fields up to 9 Tesla.
- Proton-Induced X-ray Emission Spectroscopy to detect magnetic impurities.
Main Results:
- Defect-related states with magnetic degrees of freedom were observed in LaAlO3 and other rare-earth perovskites.
- These states were identified as energy levels above the valence band maximum (~140 meV) and mid-gap states (~2.3 eV).
- No magnetic impurities were detected in LaAlO3, attributing the magnetic states to cationic/anionic vacancies or anti-site defects.
Conclusions:
- The observed magnetic states in LaAlO3 are attributed to intrinsic defects.
- An empirical rule suggests that magnetic-field-sensitive transitions require specific arrangements of heavy elements and oxygen planes.
- Defect engineering in rare-earth perovskites offers potential for tunable magneto-optic applications.
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