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Room-temperature ferroelectric switching of spin-to-charge conversion in germanium telluride

Nature Electronics volume 4, pages 740–747 (2021)Cite this article

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Abstract

The development of spintronic devices has been limited by the poor compatibility between semiconductors and ferromagnetic sources of spin. The broken inversion symmetry of some semiconductors may allow for spin–charge interconversion, but its control by electric fields is volatile. This has led to interest in ferroelectric Rashba semiconductors, which combine semiconductivity, large spin–orbit coupling and non-volatility. Here we report room-temperature, non-volatile ferroelectric control of spin-to-charge conversion in epitaxial germanium telluride films. We show that ferroelectric switching by electrical gating is possible in germanium telluride, despite its high carrier density. We also show that spin-to-charge conversion has a similar magnitude to what is observed with platinum, but the charge current sign is controlled by the orientation of ferroelectric polarization. Comparison between theoretical and experimental data suggests that the inverse spin Hall effect plays a major role in switchable conversion.

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Fig. 1: Ferroelectric switching of GeTe by electrical gating and electric readout of the state.
Fig. 2: Resistive modulation in Ti/GeTe junctions.
Fig. 3: Ferroelectric control of SCC in GeTe investigated by SP-FMR.
Fig. 4: Theoretical evidence of switchable spin–charge interconversion in GeTe and prototypical device.

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Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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Acknowledgements

C.R. acknowledges financial support by Fondazione Cariplo and Regione Lombardia (grant no. 2017-1622 (ECOS)). C.R. and S. Picozzi acknowledge support from the Italian Ministry of Universities and Research (MUR) under the PRIN programme, project no. 2017YCTB59 (towards ferroelectricity in two dimensions (TWEET)). M.B. acknowledges support from the European Research Council through the Advanced Grant ‘FRESCO’ no. 833973. J.S. acknowledges Rosalind Franklin Fellowship from the University of Groningen. We acknowledge financial support by ANR French National Research Agency Toprise (no. ANR-16-CE24-0017), ANR French National Research Agency OISO (no. ANR-17-CE24-0026), ANR French National Research Agency CONTRABASS (no. ANR-20-CE24-0023) and the Laboratoire d’excellence LANEF (no. ANR-10-LABX-51-01). We are grateful to the EPR facilities available at the National TGE RPE facilities (no. IR 3443) and to the High Performance Computing Center at the University of North Texas and the Texas Advanced Computing Center at the University of Texas, Austin. We acknowledge A. Brenac, J.-F. Jacquot, C. Lombard and S. Gambarelli for their help and advice on the FMR measurement setup. We are grateful to O. Klein, M. Jamet, F. Yu, T. Guillet, M. Guimarães, D. Di Sante, F. Pezzoli, V. Garcia and S. Fusil for helpful discussions. We thank C. Stemmler and S. Behnke for technical support with the MBE system. This work was partially performed at PoliFAB, the micro- and nanofabrication facility of the Politecnico di Milano.

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Author notes

  1. Sara Varotto

    Present address: Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, France

Authors and Affiliations

  1. Dipartimento di Fisica, Politecnico di Milano, Milan, Italy

    Sara Varotto, Luca Nessi, Simone Petrò, Federico Fagiani, Alessandro Novati, Matteo Cantoni, Daniela Petti, Edoardo Albisetti, Riccardo Bertacco & Christian Rinaldi

  2. Istituto di Fotonica e Nanotecnologie CNR-IFN, Milan, Italy

    Luca Nessi, Matteo Cantoni, Riccardo Bertacco & Christian Rinaldi

  3. Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Berlin, Germany

    Stefano Cecchi & Raffaella Calarco

  4. Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands

    Jagoda Sławińska

  5. Department of Physics, University of North Texas, Denton, TX, USA

    Jagoda Sławińska & Marco Buongiorno Nardelli

  6. Univ. Grenoble Alpes, CNRS, CEA, Spintec, Grenoble, France

    Paul Noël, Jean-Philippe Attané & Laurent Vila

  7. Department of Physics, Fluminense Federal University, Niterói, Brazil

    Marcio Costa

  8. Consiglio Nazionale delle Ricerche–Istituto per la Microelettronica e Microsistemi (CNR-IMM), Rome, Italy

    Raffaella Calarco

  9. Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, Palaiseau, France

    Manuel Bibes

  10. Consiglio Nazionale delle Ricerche, CNR-SPIN c/o Università G. D’Annunzio, Chieti, Italy

    Silvia Picozzi

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Contributions

C.R. conceived the experiment and coordinated the research work with the support of R.B. S.C. and R.C. grew the GeTe/Si samples and performed the structural characterization. S.V., L.N, S. Petrò and A.N. fabricated the devices for electrical characterization and PFM experiments. S.V., C.R. and L.N. performed the PFM imaging. F.F. performed the measurements of switching speed. S. Petrò, C.R., S.V., D.P., E.A. and M. Cantoni grew the heterostructures for the SP experiments, while S.V., P.N., L.V. and J.-P.A. performed the experiments. J.S. performed the calculations with the support of M.B.N., M. Costa and S. Picozzi. C.R., M.B., J.S. and S.V. wrote the manuscript, with fundamental inputs from all the authors.

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Correspondence to Christian Rinaldi.

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Peer review information Nature Electronics thanks Chih-Huang Lai and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–4, Sections 1–6 and references.

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Varotto, S., Nessi, L., Cecchi, S. et al. Room-temperature ferroelectric switching of spin-to-charge conversion in germanium telluride. Nat Electron 4, 740–747 (2021). https://doi.org/10.1038/s41928-021-00653-2

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