Evolution of magnetoresistance behaviour at low temperatures in naturally oxidised specular spin valve systems

•Temperature dependence of R(H) of naturally oxidized SSV system was studied.•An anomalous behavior was evolved below 200 K.•Introduced the concept of density gradient in oxide region.•Origin of anomalies was attributed due to AFM ordering in spin glass state.•The effect was further confirmed by com...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2019-07, Vol.481, p.170-175
Main Authors: Sreevidya, P.V., Borole, Umesh P., Gawade, Tejaswini, Khan, Jakeer, Prajapat, C.L., Kumar, Yogesh, Barshilia, Harish C., Chowdhury, P.
Format: Article
Language:English
Subjects:
Antiferromagnetism
Coercivity
Evolution
Low temperature
Magnetism
Magnetoresistance
Magnetoresistivity
Spin glasses
Spin valves
Temperature
Temperature dependence
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Summary:•Temperature dependence of R(H) of naturally oxidized SSV system was studied.•An anomalous behavior was evolved below 200 K.•Introduced the concept of density gradient in oxide region.•Origin of anomalies was attributed due to AFM ordering in spin glass state.•The effect was further confirmed by comparing with non-magnetic MgO based system. The temperature dependent magnetoresistive behaviour of field cooled naturally oxidised specular spin valve systems has been studied in the temperature range of 300–10 K. Inconsistent to the non-specular spin valve system, an anomalous behaviour was evolved with large exchange bias and higher coercivity, below 200 K. The structural investigations inferred the formation of magnetic oxides with higher density gradient in the pinned layer, and the observed anomalous behaviour at low temperatures was correlated with the antiferromagnetic ordering of these oxides in spin glass state. The uncompensated interfacial magnetism of the nano-oxide layer was further confirmed by comparing with low temperature magnetoresistive behaviour of non-magnetic oxide based specular spin valve systems.
ISSN:0304-8853
1873-4766
DOI:10.1016/j.jmmm.2019.03.003