Absence of ferromagnetic order in high quality bulk Co-doped ZnO samples.
- Carvalho, Hugo Bonette de
- Godoy, Marcio Peron Franco de
- Pais, Rafael Witter Dias
- Mir, Mirta
- Zevallos, ?ngela Maria Ortiz de
- Iikawa, Fernando
- Brasil, Maria Jos? Santos Pompeu
- Chitta, Valmir Ant?nio
- Ferraz, Wilmar Barbosa
- Boselli, Marco Aur?lio
- Sabioni, Ant?nio Claret Soares
DOIAbstract
Bulk Zn1?xCoxO samples were synthesized via standard solid-state reaction route with different Co molar concentrations up to 21%. A detailed microstructural analysis was carried out to investigate alternative sources of ferromagnetism, such as secondary phases and nanocrystals embedded in the bulk material. Conjugating different techniques we confirmed the Zn replacement by Co ions in the wurtzite ZnO structure, which retains, however, a high crystalline quality. No segregated secondary phases neither Co-rich nanocrystals were detected. Superconducting quantum interference device magnetometry demonstrates a paramagnetic Curie?Weiss behavior with antiferromagnetic interactions. We discuss the observed room temperature paramagnetism of our sa...
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