Exchange-bias-modulated inverse superconducting spin switch in CoO/Co/YBa_(2)Cu_(3)O_(7-δ)/La_(0.7)Ca_(0.3)MnO_(3) thin film hybrids



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Nemes, Norbert Marcel and Visani, C. and Sefrioui, Zouhair and León Yebra, Carlos and Santamaría Sánchez-Barriga, Jacobo and Iglesias, M. and Mompean, F. and García Hernández, M. (2010) Exchange-bias-modulated inverse superconducting spin switch in CoO/Co/YBa_(2)Cu_(3)O_(7-δ)/La_(0.7)Ca_(0.3)MnO_(3) thin film hybrids. Physical review B, 81 (2). ISSN 1098-0121

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We examine the interplay between ferromagnetism and superconductivity in bilayer and trilayer heterostructures based on Co, YBa_(2)Cu_(3)O_(7-δ) (YBCO), and La_(0.7)Ca_(0.3)MnO_(3) (LCMO) thin films grown on SrTiO_(3) substrates with typical thicknesses of 10–15 nm. We have measured magnetoresistance below the resistive-superconducting onset of the YBCO. Naturally oxidized antiferromagnetic CoO top layer films give rise to pronounced exchange bias, modifying the coercive field of the Co by several hundred Oe. This allows separating effects at coercivity, such as stray fields, from those of parallel vs. antiparallel magnetic alignment between top and bottom ferromagnetic layers. In bilayers of Co/YBCO and of LCMO/YBCO, we observe a small magnetoresistance peak centered at the coercive field of the ferromagnetic layer of at most 20%, which we attribute to the effect of stray fields generated in the domain state of the ferromagnet. In the case of the CoO/Co/YBCO/LCMO/SrTiO_(3) trilayer, aside from the peaks at coercivity, we observe a well-defined plateau of the magnetoresistance extending between the coercive fields of the LCMO and Co, with a width that is modified by the exchange-biased Co layer. Reactivity between Co and YBCO at the interface gives rise to a progressive deterioration in the superconducting transition temperature. Aged samples display magnetoresistance peaks at the coercive fields of the Co and LCMO characteristic of stray fields without the magnetoresistance plateau between them.

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© 2010 The American Physical Society. We thank A. Goldman for fruitful discussions within the framework of the joint US-Spain NSF Materials World Network Grant No. 709584. This work has been carried out with the support of the “Ramon y Cajal” contract and Grant No. MAT2007-30922E and MAT2008–065.

Uncontrolled Keywords:Heterostructures; Superlattices; Magnetization.
Subjects:Sciences > Physics > Electricity
Sciences > Physics > Electronics
ID Code:30405
Deposited On:28 May 2015 08:24
Last Modified:10 Dec 2018 14:58

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