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DS: Fachverband Dünne Schichten
DS 44: Magnetic Coupling and Anisotropy in Thin Films (joint session MA/DS)
DS 44.9: Vortrag
Freitag, 20. März 2020, 11:45–12:00, HSZ 04
Interlayer exchange coupling in Fe/MgO[001] multilayers — •Tobias Warnatz1, Fridrik Magnus2, Sarah Sanz1, Hasan Ali3, Klaus Leifer3, and Björgvin Hjörvarsson1 — 1Department of Physics and Astronomy, Uppsala University, Sweden — 2Science Institute, University of Iceland, Reykjavik, Iceland — 3Department of Engineering Sciences, Uppsala University, Sweden
Fe/MgO/Fe tunnel junctions are well known for their magnetoresistance, but their interlayer exchange coupling (IEC) [1] is less explored. Recently, we reported a sequential magnetic switching in interlayer exchange coupled Fe/MgO[001] superlattices [2]. The presented results were consistent with a beyond nearest neighbor IEC. Here, we report the first systematic investigation on the range of IEC in epitaxial Fe/MgO[001] multilayers. For that, samples with various Fe/MgO bilayer repetitions (N) were grown on single crystalline MgO(001) substrates. Hystereses curves with discrete magnetization steps were obtained, consistent with our previous results [2]. Taking only nearest-neighbor interactions into account, a reduction of the IEC by a factor of (1-1/N) should be observed [3] (the missing neighbor of the outermost layers becomes less important for many N). Our results deviate drastically from this prediction and verify a strong contribution from beyond nearest neighbor interactions. The results are essential for the understanding of the IEC in tunnel junctions and could even serve as a base for the development of three-dimensional data structures.
[1] Phys. Rev. Lett. 89, 106602 (2002) [2] Phys. Rev. B 97, 74424 (2018) [3] Appl. Phys. Lett. 58, pp. 1473-1475 (1991)