Negative magnetoresistance in dual spin valve structures with a synthetic antiferromagnetic free layer
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C. Fowley, BS Chun, JMD Coey 'Negative magnetoresistance in dual spin valve structures with a synthetic antiferromagnetic free layer' in IEEE Transactions on Magnetics, 45, (6), 2009, pp 2403-2406Download Item:
Abstract:
Giant magnetoresistance (GMR) in spin valves is due to spin-dependent scattering occurring at ferromagnet/normal metal (F/N) interfaces and/or in the ferromagnetic layers. In a spin valve with a typical F/N/F structure where the spin scattering asymmetry factor (alpha) of both F/N interfaces is the same (more or less than 1), the GMR is expected to be positive. If alpha is greater than one at one F/N interface and less than one at the other F/N interface, however, the GMR is expected to be negative. Here, we show that the F1/Cu/SAF/Cu/F2/IrMn dual spin valve structure exhibits negative GMR, where F1 and F2 are CoFe and SAF = CoFe/Ru t/CoFe, due to both opposite electron spin scattering asymmetry factor at the CoFe/Ru/CoFe interfaces as well as the electrical separation of the overall structure into two GMR spin valves connected in parallel. A GMR of 6% is observed in the structure without the Ru spacer layer, insertion of a 0.6 nm thick Ru in the SAF results in a negative GMR ratio of -3% , which becomes positive again at the Ru thickness of 0.8 nm, the oscillation from positive to negative MR is consistent with interlayer exchange coupling period across the Ru spacer.
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Science Foundation Ireland
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http://people.tcd.ie/jcoeyDescription:
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Author: FOWLEY, CIARAN; COEY, JOHN MICHAEL DAVID
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IEEE Transactions on Magnetics45
6
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http://dx.doi.org/10.1109/TMAG.2009.2018589Metadata
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