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Direct probing of the exchange interaction at buried interfaces

Abstract

The fundamental interactions between magnetic moments at interfaces have an important impact on the properties of layered magnetic structures. Hence, a direct probing of these interactions is highly desirable for understanding a wide range of phenomena in low-dimensional solids. Here we propose a method for probing the magnetic exchange interaction at buried interfaces using spin-polarized electrons and taking advantage of the collective nature of elementary magnetic excitations (magnons). We demonstrate that, for the case of weak coupling at the interface, the low-energy magnon mode is mainly localized at the interface. Because this mode has the longest lifetime of the modes and has a finite spectral weight across the layers on top, it can be probed by electrons. A comparison of experimental data and first-principles calculations leads to the determination of the interface exchange parameters. This method may help the development of spectroscopy of buried magnetic interfaces.

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Figure 1: Experimental scheme, magnetic hysteresis loop, typical spectra and magnon dispersion relation.
Figure 2: Calculated magnon dispersion relation and spectral density for six atomic layers of Fe film on Ir(001) and site-resolved exchange coupling.
Figure 3: Lifetime of different magnon modes.

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Acknowledgements

A.E. acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG priority programme SPP 1538 ‘Spin Caloric Transport’). The calculations were performed at the Rechenzentrum Garching of the Max Planck Society.

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Authors

Contributions

Kh.Z. supervised the project, conceived and planned the experiments, participated in the analysis of the experimental data and wrote the paper. T.-H.C. carried out the experiments and analysed the experimental data. A.E. and P.B. performed the theoretical calculations. A.E. analysed the theoretical results. L.M.S. participated in the analysis of the theoretical results, the development of the structure of the paper and in writing the paper. H.J.Q. performed one part of the experiments and analysed the experimental data. Y.Z. contributed to the experiments. J.K. supervised the project. All authors contributed to the discussion of the results and improving the manuscript.

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Correspondence to Kh. Zakeri.

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Zakeri, K., Chuang, TH., Ernst, A. et al. Direct probing of the exchange interaction at buried interfaces. Nature Nanotech 8, 853–858 (2013). https://doi.org/10.1038/nnano.2013.188

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