Large-area van der Waals epitaxy of ferromagnetic Fe3GeTe2 films on graphene

Magnetic two-dimensional (2D) materials are promising building blocks for realizing ultra-compact spintronic devices with enhanced performance. Their study is also expected to open new perspectives on a more versatile modulation of magnetic properties, beyond what can be achieved in traditional three-dimensional (3D) magnetic thin films and superlattices. In particular, combining magnetic 2D materials with other 2D crystals such as graphene and transition metal dichalcogenides (TMDCs) to create van der Waals (vdW) heterostructures offers great potential to tailor magnetism via proximity-induced phenomena. To date, experimental research on 2D magnets and related vdW heterostructures has mainly concentrated on micrometer-sized flakes exfoliated from bulk crystals, which are not scalable and incompatible with standard device fabrication. Hence, exploiting large-scale synthesis of such material systems is greatly demanded for the development of atomically thin magnetic vdW materials to be implemented into future applications.

Figure 1. Reflection high energy electron diffraction patterns taken along the [11-20] direction before (a) and after (b) the growth of a 10-nm-thick Fe₃GeTe₂ film on graphene/SiC(0001). The narrow streaks appearing in (b) indicate epitaxial growth of a 2D film with smooth surface and good structural quality. (c) Transverse resistance RXY of a 1 cm² Fe₃GeTe₂/graphene van der Pauw structure during downward and upward magnetic field sweeps at different temperatures. The anomalous Hall effect is detected as a square-shape hysteresis loop, which reflects the ferromagnetic order in the Fe₃GeTe₂ film with a strong perpendicular magnetic anisotropy.

Here, we report on the vdW epitaxy of the ferromagnetic metal Fe₃GeTe₂—a 2D crystal with tunable properties and great potential for room temperature ferromagnetism—via molecular beam epitaxy on a graphene/SiC(0001) template. Morphological and structural characterization confirmed the realization of large-area, continuous Fe₃GeTe₂/graphene heterostructure films with high structural and interface quality. Additionally, magneto-transport and X-ray magnetic circular dichroism investigations revealed a robust out-of-plane ferromagnetism in the films with a Curie temperature around 220 K, which is comparable to flakes exfoliated from state-of-the-art bulk single crystals. These results are highly relevant for further research on wafer-scale growth of vdW systems containing magnetic 2D crystals for the realization of multifunctional, atomically thin devices. By combining Fe₃GeTe₂ with other selected 2D crystals including TMDCs and h-BN, which can also be grown by precise methods such as MBE, we envision the realization of spintronic devices with dimensions and performance not achievable with conventional bulk materials.

1	Autor	J. M. J. Lopes , D. Czubak , E. Zallo , A.I. Figueroa , C. Guillemard , M. Valvidares , J.R. Zuazo , J. López-Sanchéz , S.O. Valenzuela , M. Hanke , M. Ramsteiner
	Titel	Large-area van der Waals epitaxy and magnetic characterization of Fe 3 GeTe 2 films on graphene
	Source	2D Mater. , 8 , 041001 ( 2021 )
DOI : 10.1088/2053-1583/ac171d \| arxiv: arXiv:2104.09184 \| 3248 Cite : Bibtex RIS @article{ author = { J. M. J. Lopes and D. Czubak and E. Zallo and A.I. Figueroa and C. Guillemard and M. Valvidares and J.R. Zuazo and J. López-Sanchéz and S.O. Valenzuela and M. Hanke and M. Ramsteiner }, title = { Large-area van der Waals epitaxy and magnetic characterization of Fe 3 GeTe 2 films on graphene }, journal = { 2D Materials }, volume = { 8 }, year = { 2021 }, pages = { 041001 } } J. M. J. Lopes, D. Czubak, E. Zallo, A.I. Figueroa, C. Guillemard, M. Valvidares, J.R. Zuazo, J. López-Sanchéz, S.O. Valenzuela, M. Hanke, and M. Ramsteiner TY - JOUR AU - J. M. J. Lopes AU - D. Czubak AU - E. Zallo AU - A.I. Figueroa AU - C. Guillemard AU - M. Valvidares AU - J.R. Zuazo AU - J. López-Sanchéz AU - S.O. Valenzuela AU - M. Hanke AU - M. Ramsteiner TI - Large-area van der Waals epitaxy and magnetic characterization of Fe 3 GeTe 2 films on graphene JF - 2D Materials JA - 2D Mater. J1 - VL - 8 SP - 041001 PY - 2021/08/11

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Large-area van der Waals epitaxy of ferromagnetic Fe3GeTe2 films on graphene

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