Role of defects on the magnetic behaviour of the geometrically frustrated spinel ZnFe^sub 2^O^sub 4

Defective zinc ferrites ZnFe2O4-δ obtained by vacuum annealing bulk Zn-ferrite at different temperatures TAnn were investigated by using XANES at Zn-K, Fe-K and XMCD at Fe-L2,3 edges, static and dynamic magnetic measurements. The cation inversion that confers to the starting ferrite a weak ferromagn...

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Bibliographic Details
Published in:Journal of alloys and compounds 2018-07, Vol.752, p.289
Main Authors: Rodríguez, KL Salcedo, Stewart, SJ, Zélis, PM Mendoza, Pasquevich, GA, Torres, CE Rodríguez
Format: Article
Language:English
Subjects:
Defects
Electromagnetics
Ferromagnetism
Geometry
Glass
Magnetic measurement
Magnetic properties
Spinel
Temperature effects
Vacuum annealing
Zinc
Zinc ferrites
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Summary:Defective zinc ferrites ZnFe2O4-δ obtained by vacuum annealing bulk Zn-ferrite at different temperatures TAnn were investigated by using XANES at Zn-K, Fe-K and XMCD at Fe-L2,3 edges, static and dynamic magnetic measurements. The cation inversion that confers to the starting ferrite a weak ferromagnetic response is progressively lost when TAnn surpasses 250 °C. Consequently, there is a detriment of the magnetic response that reaches its lower value for TAnn around 370 °C, being the latter coincident with a negligible non-equilibrium occupancy. Above TAnñ 450 °C the ferrite progressively enhances its magnetic response. In such case, even though Zn and Fe occupy non-equilibrium sites at surface regions, the deficiency of oxygen predominates over inversion and the former triggers an increment of the magnetic coupling between Fe3+ at octahedral spinel sites. We discuss the magnetic results that account for spin-glass and/or cluster-glass behavior of this geometrically frustrated compound as due to the randomness and frustration introduced by local defects.
ISSN:0925-8388
1873-4669