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Phase-pure two-dimensional FexGeTe2 magnets with near-room-temperature TC

An Erratum to this article was published on 25 June 2021

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Abstract

Two-dimensional (2D) ferromagnets with out-of-plane (OOP) magnetic anisotropy are potential candidates for realizing the next-generation memory devices with ultra-low power consumption and high storage density. However, a scalable approach to synthesize 2D magnets with OOP anisotropy directly on the complimentary metal-oxide semiconductor (CMOS) compatible substrates has not yet been mainly explored, which hinders the practical application of 2D magnets. This work demonstrates a cascaded space confined chemical vapor deposition (CS-CVD) technique to synthesize 2D FexGeTe2 ferromagnets. The weight fraction of iron (Fe) in the precursor controls the phase purity of the as-grown FexGeTe2. As a result, high-quality Fe3GeTe2 and Fe5GeTe2 flakes have been grown selectively using the CS-CVD technique. Curie temperature (TC) of the as-grown FexGeTe2 can be up to ∼ 280 K, nearly room temperature. The thickness and temperature-dependent magnetic studies on the Fe5GeTe2 reveal a 2D Ising to 3D XY behavior. Also, Terahertz spectroscopy experiments on Fe5GeTe2 display the highest conductivity among other FexGeTe2 2D magnets. The results of this work indicate a scalable pathway for the direct growth and integration of 2D ternary magnets on CMOS-based substrates to develop spintronic memory devices.

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Acknowledgements

G. K., Z. Z., F. H., and A. L., contributed equally to this work. G. K and Z. L. conceived the research. G. K., W. Y., H. W. synthesized the samples. G. K., A. L., L. K., Z. N., and S. Y. performed the terahertz measurements and analyzed the THz results. F. H. and J. L. carried out STEM studies. Z. Z. and G. W. carried out the RMCD measurements. G. K. and T. S. performed the XPS characterizations. X. X. and X. L. carried out the DFT calculations. All authors helped to analyze data, discussed and interpreted detailed results, and co-wrote the manuscript.

This work was supported from National Research Foundation Singapore programme NRF-CRP22-2019-0007, NRF-CRP22-2019-0004 and NRF-CRP21-2018-0007. This work was also supported by the Ministry of Education, Singapore, under its AcRF Tier 3 Programme ‘Geometrical Quantum Materials’ (MOE2018-T3-1-002), AcRF Tier 2 (MOE2019-T2-2-105) and AcRF Tier 1 RG4/17 and RG7/18. We also thank the funding support from National Research foundation (NRF-CRP22-2019-0004).

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Correspondence to Xingji Li or Weibo Gao or Zheng Liu.

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Nair, G.K.R., Zhang, Z., Hou, F. et al. Phase-pure two-dimensional FexGeTe2 magnets with near-room-temperature TC. Nano Res. (2021). https://doi.org/10.1007/s12274-021-3502-0

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Keywords

  • cascaded space confined chemical vapor deposition (CVD)
  • van der Waals (vdW)
  • ferromagnetism
  • out of plane anisotropy
  • iron germanium telluride
  • terahertz