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Title: Study of the relation between oxygen vacancies and ferromagnetism in Fe-doped TiO{sub 2} nano-powders

In this work, we present an experimental and theoretical study of structural and magnetic properties of Fe doped rutile TiO{sub 2} 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 Fe{sup 3+} and two oxygen vacancies in the case of Fe{sup 2+}. The saturation magnetization is almost independent of iron concentration and slightly increases with the relative fraction of Fe{sup 2+}. 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.
Authors:
; ;  [1] ;  [2] ;  [1] ;  [3] ;  [4]
  1. Departamento de Física – Facultad de Ciencias Exactas, UNLP, Instituto de Física La Plata, CCT-La Plata, CONICET, CC 67, 1900 La Plata (Argentina)
  2. Laboratorio de Sólidos Amorfos, INTECIN-CONICET, Facultad de Ingeniería, UBA, Av. Paseo Colón 850, Buenos Aires C1063ACV (Argentina)
  3. (UNNOBA), Monteagudo 2772, Pergamino. CP 2700 Buenos Aires (Argentina)
  4. Depto. de Física, Comisión Nacional de Energía Atómica, Av. del Libertador 8250, 1429 Buenos Aires (Argentina)
Publication Date:
OSTI Identifier:
22304150
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; CARRIERS; COUPLING; DIMERS; DOPED MATERIALS; FERROMAGNETISM; GRAIN BOUNDARIES; IRON ADDITIONS; MAGNETIC PROPERTIES; MAGNETIZATION; NANOPARTICLES; NANOSTRUCTURES; OXYGEN; POWDERS; RUTILE; SATURATION; TITANIUM OXIDES; VACANCIES