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Electric-field-controlled ferromagnetism in high-Curie-temperature Mn0.05Ge0.95 quantum dots

Abstract

Electric-field manipulation of ferromagnetism has the potential for developing a new generation of electric devices to resolve the power consumption and variability issues in today’s microelectronics industry. Among various dilute magnetic semiconductors (DMSs), group IV elements such as Si and Ge are the ideal material candidates because of their excellent compatibility with the conventional complementary metal–oxide–semiconductor (MOS) technology. Here we report, for the first time, the successful synthesis of self-assembled dilute magnetic Mn0.05Ge0.95 quantum dots with ferromagnetic order above room temperature, and the demonstration of electric-field control of ferromagnetism in MOS ferromagnetic capacitors up to 100 K. We found that by applying electric fields to a MOS gate structure, the ferromagnetism of the channel layer can be effectively modulated through the change of hole concentration inside the quantum dots. Our results are fundamentally important in the understanding and to the realization of high-efficiency Ge-based spin field-effect transistors.

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Figure 1: Structural properties of Mn0.05Ge0.95 quantum dots grown on a p-type Si substrate.
Figure 2: Magnetic properties of Mn0.05Ge0.95 quantum dots grown on a p-type Si substrate.
Figure 3: AFM and MFM images of Mn0.05Ge0.95 quantum dots measured at 320 K.
Figure 4: Characterization and simulation of a MOS device using Mn0.05Ge0.95 quantum dots as the channel layer.
Figure 5: Electric-field-controlled ferromagnetism.

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Acknowledgements

We gratefully acknowledge the financial support from the Western Institute of Nanoelectronics (WIN), the Intel Spin–Gain FET project and the Australian Research Council. We thank N. Dmitri of Intel Incorporation for his advice on our experiments.

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Contributions

F.X., A.P.J. and K.L.W. conceived and designed the experiments. F.X., Y.W., J.K., A.H. and J.T. carried out the experiments. F.X., Y.W., J.Z., and K.L.W. wrote the manuscript with partial contribution from A.P.J. and J.K. All authors discussed the results and commented on the manuscript. F.X. and Y.W. contributed equally to this research.

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Correspondence to Kang L. Wang.

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Xiu, F., Wang, Y., Kim, J. et al. Electric-field-controlled ferromagnetism in high-Curie-temperature Mn0.05Ge0.95 quantum dots. Nature Mater 9, 337–344 (2010). https://doi.org/10.1038/nmat2716

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