Next Article in Journal
Physical Modeling of Cross Wedge Rolling Limitations
Previous Article in Journal
Recycling Aggregates for Self-Compacting Concrete Production: A Feasible Option
Previous Article in Special Issue
Magnetic Behavior in TiS3 Nanoribbon
Open AccessArticle

Spin-Glass Transitions in Zn1-xFexO Nanoparticles

1
Departamento de Física, Maringá State University, Av. Colombo, 5790–Zona 7, Maringá, PR 87020-900, Brazil
2
Instituto de Física, Federal University of Rio Grande do Sul, Porto Alegre, RS 91501-970, Brazil
3
Departamento de Física, Federal University of Espírito Santo, Vitória, ES 29075-010, Brazil
*
Author to whom correspondence should be addressed.
Materials 2020, 13(4), 869; https://doi.org/10.3390/ma13040869
Received: 15 December 2019 / Revised: 5 January 2020 / Accepted: 6 January 2020 / Published: 14 February 2020
Monophasic Zn1-xFexO nanoparticles with wurtzite structure were synthesized in the 0 ≤ x ≤ 0.05 concentration range using a freeze-drying process followed by heat treatment. The samples were characterized regarding their optical, structural, and magnetic properties. The analyses revealed that iron doping of the ZnO matrix induces morphological changes in the crystallites. Iron is substitutional for zinc, trivalent and distributed in the wurtzite lattice in two groups: isolated iron atoms and iron atoms with one or more neighboring iron atoms. It was also shown that the energy band gap decreases with a higher doping level. The samples are paramagnetic at room temperature, but they undergo a spin-glass transition when the temperature drops below 75 K. The magnetic frustration is attributed to the competition of magnetic interactions among the iron moments. There are a superexchange interaction and an indirect exchange interaction that is provided by the spin (and charge) itinerant carriers in a spin-polarized band situated in the vicinity of the Fermi level of the Fe-doped ZnO semiconductor. The former interaction actuates for an antiferromagnetic coupling among iron ions, whereas the latter constitutes a driving force for a ferromagnetic coupling that weakens, decreasing the temperature. Our results strongly contribute to the literature because they elucidate the controversies reported in the literature for the magnetic state of the Fe-doped ZnO system. View Full-Text
Keywords: Fe-doped ZnO; dilute magnetic semiconductor; spin-glass; energy bands; X-ray diffraction; diffused reflectance spectroscopy; magnetic properties; Mössbauer spectroscopy Fe-doped ZnO; dilute magnetic semiconductor; spin-glass; energy bands; X-ray diffraction; diffused reflectance spectroscopy; magnetic properties; Mössbauer spectroscopy
Show Figures

Figure 1

MDPI and ACS Style

Felipe S. Tupan, L.; Valerio-Cuadros, M.I.; Oliveira, A.A.; Barco, R.; Ivashita, F.F.; Lopes, L.F.; Passamani, E.C.; Paesano, A., Jr. Spin-Glass Transitions in Zn1-xFexO Nanoparticles. Materials 2020, 13, 869.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop