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Electric-field-assisted switching in magnetic tunnel junctions

Abstract

The advent of spin transfer torque effect accommodates site-specific switching of magnetic nanostructures by current alone without magnetic field. However, the critical current density required for usual spin torque switching remains stubbornly high around 106–107 A cm−2. It would be fundamentally transformative if an electric field through a voltage could assist or accomplish the switching of ferromagnets. Here we report electric-field-assisted reversible switching in CoFeB/MgO/CoFeB magnetic tunnel junctions with interfacial perpendicular magnetic anisotropy, where the coercivity, the magnetic configuration and the tunnelling magnetoresistance can be manipulated by voltage pulses associated with much smaller current densities. These results represent a crucial step towards ultralow energy switching in magnetic tunnel junctions, and open a new avenue for exploring other voltage-controlled spintronic devices.

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Figure 1: Electric-field-assisted switching in a CoFeB/MgO/CoFeB MTJ with interfacial perpendicular magnetic anisotropy.
Figure 2: Manipulation of giant tunnelling resistance by electric field.
Figure 3: Effect of electric field in MTJs with different perpendicular anisotropy energies.
Figure 4: Electric-field-induced unipolar switching.

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Acknowledgements

This work is supported by the National Science Foundation under grant No DMR05-20491.

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Contributions

W-G.W. and C.L.C. conceived and designed the experiments. W-G.W. and M.L. fabricated the MTJ films and nanopillars. M.L., S.H. and W-G.W. measured transport and magnetic properties of the samples. C.L.C. supervised the study. W-G.W. and C.L.C. wrote the manuscript and all authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Wei-Gang Wang or C. L. Chien.

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The authors declare no competing financial interests.

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Wang, WG., Li, M., Hageman, S. et al. Electric-field-assisted switching in magnetic tunnel junctions. Nature Mater 11, 64–68 (2012). https://doi.org/10.1038/nmat3171

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