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Georgopoulou-Kotsaki E, Pappas P, Lintzeris A, Tsipas P, Fragkos S, Markou A, Felser C, Longo E, Fanciulli M, Mantovan R, Mahfouzi F, Kioussis N, Dimoulas A. Significant enhancement of ferromagnetism above room temperature in epitaxial 2D van der Waals ferromagnet Fe 5-δGeTe 2/Bi 2Te 3 heterostructures. Nanoscale 2023; 15:2223-2233. [PMID: 36625389 DOI: 10.1039/d2nr04820e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Two-dimensional (2D) van der Waals (vdW) ferromagnetic metals FexGeTe2 with x = 3-5 have raised significant interest in the scientific community. Fe5GeTe2 shows prospects for spintronic applications since the Curie temperature Tc has been reported near or higher than 300 K. In the present work, epitaxial Fe5-δGeTe2 (FGT) heterostructures were grown by Molecular Beam Epitaxy (MBE) on insulating crystalline substrates. The FGT films were combined with Bi2Te3 topological insulator (TI) aiming to investigate the possible beneficial effect of the TI on the magnetic properties of FGT. FGT/Bi2Te3 films were compared to FGT capped only with AlOx to prevent oxidation. SQUID and MOKE measurements revealed that the growth of Bi2Te3 TI on FGT films significantly enhances the saturation magnetization of FGT as well as the Tc well above room temperature (RT) reaching record values of 570 K. First-principles calculations predict a shift of the Fermi level and an associated enhancement of the majority spin (primarily) as well as the total density of states at the Fermi level suggesting that effective doping of FGT from Bi2Te3 could explain the enhancement of ferromagnetism in FGT. It is also predicted that strain induced stabilization of a high magnetic moment phase in FGT/Bi2Te3 could be an alternative explanation of magnetization and Tc enhancement. Ferromagnetic resonance measurements evidence an enhanced broadening in the FGT/Bi2Te3 heterostructure when compared to FGT. We obtain a large spin mixing conductance of g↑↓eff = 4.4 × 1020 m-2, which demonstrates the great potential of FGT/Bi2Te3 systems for spin-charge conversion applications at room temperature.
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Affiliation(s)
- E Georgopoulou-Kotsaki
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15784, Athens, Greece
| | - P Pappas
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
| | - A Lintzeris
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
- Department of Physics, National Technical University of Athens, School of Applied Mathematical and Physical Sciences, 15780, Athens, Greece
| | - P Tsipas
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
| | - S Fragkos
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
- Department of Mechanical Engineering, University of West Attica, 12241 Athens, Greece
| | - A Markou
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - C Felser
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - E Longo
- Institute for Microelectronics and Microsystems, CNR-IMM Unit of Agrate Brianza, Via C. Olivetti 2, 20864 Agrate Brianza, Italy
| | - M Fanciulli
- Department of Material Science, University of Milano Bicocca, Via R. Cozzi 55, Milan 20125, Italy
| | - R Mantovan
- Institute for Microelectronics and Microsystems, CNR-IMM Unit of Agrate Brianza, Via C. Olivetti 2, 20864 Agrate Brianza, Italy
| | - F Mahfouzi
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330-8268, USA
| | - N Kioussis
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330-8268, USA
| | - A Dimoulas
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
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