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Control of quantum magnets by atomic exchange bias

Nature Nanotechnology volume 10, pages 40–45 (2015)Cite this article

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Abstract

Mixing of discretized states in quantum magnets has a radical impact on their properties. Managing this effect is key for spintronics in the quantum limit. Magnetic fields can modify state mixing and, for example, mitigate destabilizing effects in single-molecule magnets1,2. The exchange bias field3,4 has been proposed as a mechanism for localized control of individual nanomagnets5,6. Here, we demonstrate that exchange coupling with the magnetic tip of a scanning tunnelling microscope provides continuous tuning of spin state mixing in an individual nanomagnet. By directly measuring spin relaxation time with electronic pump–probe spectroscopy7, we find that the exchange interaction acts analogously to a local magnetic field that can be applied to a specific atom. It can be tuned in strength by up to several tesla and cancel external magnetic fields, thereby demonstrating the feasibility of complete control over individual quantum magnets with atomically localized exchange coupling.

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Figure 1: Spin relaxation time variations of an Fe trimer.
Figure 2: Exchange interaction control of the spin relaxation time.
Figure 3: Model for the local exchange bias field of the magnetic tip.
Figure 4: Spin state control using the tip-induced exchange bias field.

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Acknowledgements

The authors thank S. Heinze, C. Hübner and D. Pfannkuche for discussions, and E. Weckert and H. Dosch (Deutsches Elektronen-Synchrotron) for providing laboratory space. D.J.C. and J.A.J.B. acknowledge postdoctoral fellowships from the Alexander von Humboldt Foundation. J.A.J.B. acknowledges support from the Natural Sciences and Engineering Research Council of Canada.

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Authors and Affiliations

  1. Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, 22761, Germany

    Shichao Yan, Deung-Jang Choi, Jacob A. J. Burgess, Steffen Rolf-Pissarczyk & Sebastian Loth

  2. Max Planck Institute for Solid State Research, Stuttgart, 70569, Germany

    Shichao Yan, Deung-Jang Choi, Jacob A. J. Burgess, Steffen Rolf-Pissarczyk & Sebastian Loth

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  1. Shichao Yan
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  2. Deung-Jang Choi
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Contributions

S.Y. and S.L. conceived the experiment. S.Y. carried out the experiments and performed the analysis and calculations. All authors participated in the experimental work and contributed to writing the manuscript.

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Correspondence to Shichao Yan or Sebastian Loth.

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Yan, S., Choi, DJ., Burgess, J. et al. Control of quantum magnets by atomic exchange bias. Nature Nanotech 10, 40–45 (2015). https://doi.org/10.1038/nnano.2014.281

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