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Published on: November 11, 2013
Substitutional disorder and charge localization in manganites
Eduardo V Castro1, J M B Lopes Dos Santos
1CFP and Departamento de Física, Faculdade de Ciências Universidade do Porto, P-4169-007 Porto, Portugal. evcastro@fc.up.pt
Summary
Substitutional disorder in manganites can induce a metal-insulator transition, even at intermediate doping levels. This finding is crucial for understanding colossal magnetoresistance effects in these materials.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid State Chemistry
Background:
- Manganites (RE(1-x)AE(x)MnO(3)) exhibit complex electronic properties due to the random distribution of rare-earth (RE) and alkaline-earth (AE) elements.
- This atomic disorder leads to correlated shifts in charge carrier site energies within the manganese (Mn) sites.
Purpose of the Study:
- To investigate the metal-insulator transition in manganites considering both diagonal and double-exchange hopping disorder.
- To analyze the influence of temperature, doping concentration (x), and the paramagnetic-ferromagnetic transition on this phenomenon.
Main Methods:
- Development of a realistic theoretical model incorporating diagonal disorder and double-exchange hopping.
- Simulation and analysis of the metal-insulator transition across varying temperatures and doping levels (x).
Main Results:
- Contrary to previous studies, the model suggests that disorder-induced metal-to-insulator transitions are possible at intermediate doping (x ≈ 0.2-0.4).
- These transitions can occur concurrently with the ferromagnetic to paramagnetic phase transition.
Conclusions:
- Substitutional disorder plays a significant role in the electronic behavior of manganites.
- Disorder effects must be considered when explaining the colossal magnetoresistance properties observed in these materials.
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