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Origin of the inverse spin-switch behavior in manganite/cuprate/manganite trilayers

2008; American Physical Society; Volume: 78; Issue: 9 Linguagem: Inglês

10.1103/physrevb.78.094515

1550-235X

N. M. Nemes, M. García‐Hernández, S. G. E. te Velthuis, Axel Hoffmann, C. Visani, Javier García‐Barriocanal, V. Peña, D. Arias, Z. Sefrioui, C. León, J. Santamarı́a,

Advanced Condensed Matter Physics

We studied ferromagnet/superconductor/ferromagnet trilayers based on ${\text{La}}_{0.7}{\text{Ca}}_{0.3}{\text{MnO}}_{3}$ manganite and ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ (YBCO) high-${T}_{c}$ cuprate with magnetoresistance and magnetization measurements. We find an inverse superconducting spin-switch behavior, where superconductivity is favored for parallel alignment of the magnetization in the ferromagnetic layers. We argue that this inverse superconducting spin switch originates from the transmission of spin-polarized carriers into the superconductor. In this picture, the thickness dependence of the magnetoresistance yields the spin-diffusion length in YBCO as 13 nm. A comparison of bilayers and trilayers allows ruling out the effect of the stray fields of the domain structure of the ferromagnet as the source of the inverse superconducting spin switch.