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Robust isothermal electric control of exchange bias at room temperature

Abstract

Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with high-speed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr2O3 has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr2O3 single crystal, we achieve reversible, room-temperature isothermal switching of the exchange-bias field between positive and negative values by reversing the electric field while maintaining a permanent magnetic field. This effect reflects the switching of the bulk antiferromagnetic domain state and the interface magnetization coupled to it. The switchable exchange bias sets in exactly at the bulk Néel temperature.

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Figure 1: Structural characterization.
Figure 2: Spin-polarized UPS measurements and layer-resolved DOS.
Figure 3: Isothermal electric switching of the exchange-bias field.
Figure 4: Hysteretic electric-field dependence of the exchange-bias field.

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Acknowledgements

This work is supported by NSF through Career DMR-0547887, by the Nebraska Research Initiative (NRI), by the NSF MRSEC Grant No. 0820521 and by the NRC/NRI supplement to MRSEC. K.D.B. is a Cottrell Scholar of Research Corporation. Technical help from S-Q. Shi, V. R. Shah and L. P. Yue in the calculation of DOS, taking XRD and AFM data is acknowledged, respectively. We are thankful to Crystal GmbH for providing excellent Cr2O3 single crystals.

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Contributions

X.H. and C.B. designed the study, in particular conceiving the electrically controlled exchange bias and electrically controlled magnetism. Y.W. and X.H. collected and analysed the magnetic data. N.W. led the photoemission experiments and data analysis. A.C. and E.V. supported the photoemission experiments. K.D.B. conceived the concept of roughness-insensitive surface magnetization and directed the electronic structure calculations. P.A.D. directed and conceived the photoemission experiments. C.B. directed the overall study. All authors contributed to the scientific process and the refinement of the manuscript. C.B. and X.H. wrote most of the paper.

Corresponding author

Correspondence to Christian Binek.

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The authors declare no competing financial interests.

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He, X., Wang, Y., Wu, N. et al. Robust isothermal electric control of exchange bias at room temperature. Nature Mater 9, 579–585 (2010). https://doi.org/10.1038/nmat2785

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