INVESTIGADORES
CABRERA Alejandra Fabiana
artículos
Título:
Study of the relation between oxygen vacancies and ferromagnetism in Fe-doped TiO2 nano-powders
Autor/es:
A. MUDARRA NAVARRO; C.E. RODRÍGUEZ TORRES; V. BILOVOL; A.F. CABRERA; L. ERRICO; M WEISSMANN
Revista:
JOURNAL OF APPLIED PHYSICS
Editorial:
AMER INST PHYSICS
Referencias:
Lugar: New York; Año: 2014
ISSN:
0021-8979
Resumen:
In this work we present an experimental and theoretical study of structural and magnetic properties of Fe doped rutile TiO2 nanopowders. We show that Fe-doping induces the formation of oxygen vacancies in the first-sphere coordination of iron ions, which are in +2 and +3 oxidation states. We found that Fe ions form dimers that share one oxygen vacancy in the case of Fe3+ and two oxygen vacancies in the case of Fe2+. The saturation magnetization is almost independent of iron concentration and slightly increases with the relative fraction of Fe2+. Ab initio calculations show that two Fe ions sharing an oxygen vacancy are coupled ferromagnetically, forming a bound magnetic polaron (BMP), but two neighbor BMPs are aligned antiparallel to each other. Extra electron doping plays a fundamental role mediating the magnetic coupling between the ferromagnetic entities: carriers, possibly concentrated at grain boundaries, mediate between the BMP to produce ferromagnetic alignment.
