Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2
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Abstract
Abstract In recent years, two-dimensional van der Waals materials have emerged as an important platform for the observation of long-range ferromagnetic order in atomically thin layers. Although heterostructures of such materials can be conceived to harness and couple a wide range of magneto-optical and magneto-electrical properties, technologically relevant applications require Curie temperatures at or above room temperature and the ability to grow films over large areas. Here we demonstrate the large-area growth of single-crystal ultrathin films of stoichiometric Fe5GeTe2 on an insulating substrate using molecular beam epitaxy. Magnetic measurements show the persistence of soft ferromagnetism up to room temperature in 12 nm-thick films, with a Curie temperature of 293 K, and a weak out-of-plane magnetocrystalline anisotropy. The ferromagnetic order is preserved in bilayer Fe5GeTe2, with Curie temperature decreasing to 229 K. Surface, chemical, and structural characterizations confirm the layer-by-layer growth, 5:1:2 Fe:Ge:Te stoichiometric elementary composition, and single-crystalline character of the films.
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OpenAlex topics: 2D Materials and Applications · Topological Materials and Phenomena · Heusler alloys: electronic and magnetic properties
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References (52)
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1. Mermin, N. D. & Wagner, H. Absence of ferromagnetism or antiferromagnetism in one- or two-dimensional isotropic Heisenberg models. Phys. Rev. Lett. 17, 1133–1136 (1966).10.1103/PhysRevLett.17.1133 ↗
2. Gong, C. et al. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals. Nature 546, 265–269 (2017).10.1038/nature22060 ↗
3. Huang, B. et al. Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit. Nature 546, 270–273 (2017).10.1038/nature22391 ↗
4. Wang, X. et al. Raman spectroscopy of atomically thin two-dimensional magnetic iron phosphorus trisulfide (FePS3) crystals. 2D Mater. 3, 031009 (2016).10.1088/2053-1583/3/3/031009 ↗
5. Fei, Z. et al. Two-dimensional itinerant ferromagnetism in atomically thin Fe3GeTe2. Nat. Mater. 17, 778–782 (2018).10.1038/s41563-018-0149-7 ↗
6. Seo, J. et al. Nearly room temperature ferromagnetism in a magnetic metal-rich van der Waals metal. Sci. Adv. 6, eaay8912 (2020).10.1126/sciadv.aay8912 ↗
7. May, A. F. et al. Ferromagnetism near room temperature in the cleavable van der Waals crystal Fe5GeTe2. ACS Nano 13, 4436–4442 (2019).10.1021/acsnano.8b09660 ↗
8. Kim, K. et al. Large anomalous Hall current induced by topological nodal lines in a ferromagnetic van der Waals semimetal. Nat. Mater. 17, 794–799 (2018).10.1038/s41563-018-0132-3 ↗
9. You, Y. et al. Angular dependence of the topological Hall effect in the uniaxial van der Waals ferromagnet Fe3GeTe2. Phys. Rev. B 100, 134441 (2019).10.1103/PhysRevB.100.134441 ↗
10. Ding, B. et al. Observation of magnetic skyrmion bubbles in a van der Waals ferromagnet Fe3GeTe2. Nano Lett. 20, 868–873 (2020).10.1021/acs.nanolett.9b03453 ↗
11. Park, T.-E. et al. Neel-type skyrmions and their current-induced motion in van der Waals ferromagnet-based heterostructures. Phys. Rev. B 103, 104410 (2021).10.1103/PhysRevB.103.104410 ↗
12. Zhang, Y. et al. Emergence of Kondo lattice behavior in a van der Waals itinerant ferromagnet, Fe3GeTe2. Sci. Adv. 4, eaao6791 (2018).10.1126/sciadv.aao6791 ↗
13. Wang, Z. et al. Tunneling spin valves based on Fe3GeTe2/hBN/Fe3GeTe2 van der Waals heterostructures. Nano Lett. 18, 4303–4308 (2018).10.1021/acs.nanolett.8b01278 ↗
14. Freitas, D. C. et al. Ferromagnetism in layered metastable 1T-CrTe2. J. Phys. Condens. Matter 27, 176002 (2015).10.1088/0953-8984/27/17/176002 ↗
15. Zhang, X. et al. Room-temperature intrinsic ferromagnetism in epitaxial CrTe2 ultrathin films. Nat. Commun. 12, 2492 (2021).10.1038/s41467-021-22777-x ↗
16. Deiseroth, H.-J., Aleksandrov, K., Reiner, C., Kienle, L. & Kremer, R. K. Fe3GeTe2 and Ni3GeTe2—-two new layered transition-metal compounds: crystal structures, HRTEM investigations, and magnetic and electrical properties. Eur. J. Inorg. Chem. 2006, 1561–1567 (2006).10.1002/ejic.200501020 ↗
17. Chen, B. et al. Magnetic properties of layered itinerant electron ferromagnet Fe3GeTe2. J. Phys. Soc. Jpn. 82, 124711 (2013).10.7566/JPSJ.82.124711 ↗
18. Deng, Y. et al. Gate-tunable room-temperature ferromagnetism in two-dimensional Fe3GeTe2. Nature 563, 94–99 (2018).10.1038/s41586-018-0626-9 ↗
19. Tian, C. et al. Tunable magnetic properties in van der Waals crystals (Fe1−xCox)5GeTe2. Appl. Phys. Lett. 116, 202402 (2020).10.1063/5.0006337 ↗
20. Yang, M. et al. Highly enhanced Curie temperature in Ga-implanted Fe3GeTe2 van der Waals material. Adv. Quantum Technol. 3, 2000017 (2020).10.1002/qute.202000017 ↗
21. Wang, H. et al. Above room-temperature ferromagnetism in Wafer-Scale two-dimensional van der Waals Fe3GeTe2 tailored by a topological insulator. ACS Nano 14, 10045–10053 (2020).10.1021/acsnano.0c03152 ↗
22. Li, Q. et al. Patterning-induced ferromagnetism of Fe3GeTe2 van der Waals materials beyond room temperature. Nano Lett. 18, 5974–5980 (2018).10.1021/acs.nanolett.8b02806 ↗
23. May, A. F., Bridges, C. A. & McGuire, M. A. Physical properties and thermal stability of Fe5GeTe2 single crystals. Phys. Rev. Mater. 3, 104401 (2019).10.1103/PhysRevMaterials.3.104401 ↗
24. Joe, M., Yang, U. & Lee, C. First-principles study of ferromagnetic metal Fe5GeTe2. Nano Mater. Sci. 1, 299–303 (2019).10.1016/j.nanoms.2019.09.009 ↗
25. Yamagami, K. et al. Itinerant ferromagnetism mediated by giant spin polarization of the metallic ligand band in the van der Waals magnet Fe5GeTe2. Phys. Rev. B 103, L060403 (2021).10.1103/PhysRevB.103.L060403 ↗
26. May, A. F., Du, M.-H., Cooper, V. R. & McGuire, M. A. Tuning magnetic order in the van der Waals metal Fe5GeTe2 by cobalt substitution. Phys. Rev. Mater. 4, 074008 (2020).10.1103/PhysRevMaterials.4.074008 ↗
27. Li, Z. et al. Magnetic critical behavior of the van der Waals Fe5GeTe2 crystal with near room temperature ferromagnetism. Sci. Rep. 10, 15345 (2020).10.1038/s41598-020-72203-3 ↗
28. Liu, S. et al. Wafer-scale two-dimensional ferromagnetic Fe 3 GeTe 2 thin films grown by molecular beam epitaxy. npj 2D Mater. Appl. 1, 1–7 (2017).10.1038/s41699-017-0006-6 ↗
29. Burch, K. S., Mandrus, D. & Park, J.-G. Magnetism in two-dimensional van der Waals materials. Nature 563, 47–52 (2018).10.1038/s41586-018-0631-z ↗
30. Li, P. et al. Single-layer CrI3 grown by molecular beam epitaxy. Sci. Bull. 65, 1064–1071 (2020).10.1016/j.scib.2020.03.031 ↗
31. Bedoya-Pinto, A. et al. Intrinsic 2D-XY ferromagnetism in a van der Waals monolayer. Science 374, 616–620 (2021).10.1126/science.abd5146 ↗
32. Li, B. et al. Van der Waals epitaxial growth of air-stable CrSe2 nanosheets with thickness-tunable magnetic order. Nat. Mater. https://doi.org/10.1038/s41563-021-00927-2 (2021).10.1038/s41563-021-00927-2 ↗
33. Stahl, J., Shlaen, E. & Johrendt, D. The van der Waals ferromagnets Fe5–δGeTe2 and Fe5–δ–xNixGeTe2 – crystal structure, stacking faults, and magnetic properties. Z. Anorg. Allg. Chem. 644, 1923–1929 (2018).10.1002/zaac.201800456 ↗
34. Renaud, G., Barbier, A. & Robach, O. Growth, structure, and morphology of the Pd/MgO(001) interface: Epitaxial site and interfacial distance. Phys. Rev. B 60, 5872–5882 (1999).10.1103/PhysRevB.60.5872 ↗
35. Guillet, T. et al. Magnetotransport in Bi2Se3 thin films epitaxially grown on Ge(111). AIP Adv. 8, 115125 (2018).10.1063/1.5048547 ↗
36. Chen, C. T. et al. Experimental confirmation of the X-ray magnetic circular dichroism sum rules for iron and cobalt. Phys. Rev. Lett. 75, 152–155 (1995).10.1103/PhysRevLett.75.152 ↗
37. Stöhr, J. Exploring the microscopic origin of magnetic anisotropies with X-ray magnetic circular dichroism (XMCD) spectroscopy. J. Magn. Magn. Mater. 200, 470–497 (1999).10.1016/S0304-8853(99)00407-2 ↗
38. Tan, C. et al. Gate-controlled magnetic phase transition in a van der Waals magnet Fe5GeTe2. Nano Lett. 21, 5599–5605 (2021).10.1021/acs.nanolett.1c01108 ↗
39. Ohta, T. et al. Enhancement of coercive field in atomically-thin quenched Fe5GeTe2. Appl. Phys. Express 13, 043005 (2020).10.35848/1882-0786/ab7f18 ↗
40. Zhang, H. et al. Itinerant ferromagnetism in van der Waals Fe5GeTe2 crystals above room temperature. Phys. Rev. B 102, 064417 (2020).10.1103/PhysRevB.102.064417 ↗
41. Zhao, B. et al. Van der Waals Magnet based Spin-Valve Devices at Room Temperature. Preprint at https://arxiv.org/abs/2107.00310 (2021).
42. Alahmed, L. et al. Magnetism and spin dynamics in room-temperature van der Waals magnet Fe5GeTe2. 2D Mater. 8, 045030 (2021).10.1088/2053-1583/ac2028 ↗
43. Stadelmann, P. Image analysis and simulation software in transmission electron microscopy. Microsc. Microanal. 9, 60–61 (2003).10.1017/S1431927603012224 ↗
44. Allen, L. J., D׳Alfonso, A. J. & Findlay, S. D. Modelling the inelastic scattering of fast electrons. Ultramicroscopy 151, 11–22 (2015).10.1016/j.ultramic.2014.10.011 ↗
45. Ohresser, P. et al. DEIMOS: A beamline dedicated to dichroism measurements in the 350–2500 eV energy range. Rev. Sci. Instrum. 85, 013106 (2014).10.1063/1.4861191 ↗
46. Joly, L. et al. Fast continuous energy scan with dynamic coupling of the monochromator and undulator at the DEIMOS beamline. J. Synchrotron Radiat. 21, 502–506 (2014).10.1107/S1600577514003671 ↗
47. Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).10.1016/0927-0256(96)00008-0 ↗
48. Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996).10.1103/PhysRevB.54.11169 ↗
49. Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B 50, 17953–17979 (1994).10.1103/PhysRevB.50.17953 ↗
50. Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).10.1103/PhysRevB.59.1758 ↗
51. Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).10.1103/PhysRevLett.77.3865 ↗
52. Momma, K. & Izumi, F. VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. J. Appl. Cryst. 44, 1272–1276 (2011).10.1107/S0021889811038970 ↗