Exchange Bias Enhancement and Magnetic Proximity Effect in FeVO4-Fe3O4 Nanoparticles

Autor: Boris Nadgorny, Ambesh Dixit, Suvra S. Laha, Onattu D. Jayakumar, Gholam-Abbas Nazri, Ehab Abdelhamid
Rok vydání: 2019
Předmět:
Zdroj: Journal of Electronic Materials. 48:3297-3303
ISSN: 1543-186X
0361-5235
DOI: 10.1007/s11664-019-07083-z
Popis: We study the behavior of the exchange bias (EB) and the blocking temperature in an antiferromagnetic FeVO4–ferrimagnetic Fe3O4 nanocomposite system upon annealing in Ar atmosphere. Surprisingly, the blocking temperature of post-annealed samples increased to ∼ 50 K, more than two-fold compared the Neel temperature (TN = 22 K) of individual FeVO4 nanoparticles. This significant enhancement of the blocking temperature was accompanied by the corresponding increase of EB, from ∼ 50 Oe in as-prepared samples to ∼ 110 Oe in post-annealed samples. The temperature dependence of EB can be described by two approximately linear regions with different slopes, with an inflection point at T ∼ 21 K coinciding with the Neel temperature of FeVO4 nanoparticles. The region above the inflection point with non-zero EB is characterized by a weaker temperature dependence and is expanded well beyond TN. The x-ray photoemission spectroscopy measurements indicate that the surface of post-annealed Fe3O4 particles becomes oxygen deficient, which leads to a modification of the electronic, magnetic and morphological properties of the FeVO4/Fe3O4 interface. We associate this unusual behavior with a magnetic proximity effect, in which the ordering temperature of the antiferromagnetic FeVO4 nanoparticles and the corresponding exchange bias are strongly affected by the adjacent ferrimagnetic Fe3O4 layer.
Databáze: OpenAIRE
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