Magnetic Materials for Spintronics and Magnetoacoustics

Magnetic materials play a key role in modern spintronic and magnetoacoustic technologies, offering new ways to manipulate electronic and magnetic properties for advanced applications. This CReA builds upon PDI's long-standing expertise in ferromagnet/semiconductor hybrid structures (e.g., Heusler alloys like Co₂FeSi/GaAs and Fe₃Si/GaAs) and large-scale van der Waals materials (e.g., graphene/SiC and h-BN). Over the past several years, PDI's research has expanded to include layered and 2D magnetic materials, such as FeGe₂ in magnetic tunnel junctions and Fe₃GeTe₂-based heterostructures. These efforts provide a broad materials foundation for exploring spin transport, spin-dependent interactions, and magnetoacoustic coupling.

This research aims to:

• Advance spintronic materials and devices by studying spin-dependent transport, Hall effects, skyrmions, and spin-orbit/transfer torques.
• Develop high-quality magnetic materials through large-scale epitaxial growth, with a focus on 2D ferromagnets exhibiting perpendicular magnetic anisotropy for room-temperature applications.
• Engineer hybrid heterostructures that integrate magnetic materials with other 2D materials, such as graphene and WSe₂.
• Explore magnetoacoustic effects, including non-reciprocal coupling between surface acoustic waves (SAWs) and magnetization, as well as acoustic manipulation of magnetic textures.

The development of novel magnetic materials and heterostructures will contribute to the next generation of spintronic and quantum technologies, paveing the way for innovative applications in information processing, communications, and sensing technologies.

• Researchers demonstrate solution for long-term challenge that has benefits for spintronics and data storage (Press release: 29/10/2023)
• Above-room-temperature ferromagnetism in large-area van der Waals heterostructures

Granted

• EU Flagera (2024 – 2027): Enabling large tunnel magnetoresistance at room temperature in scalable epitaxial van der Waals magnet heterostructures (MagicTune). PIs: J. M. J. Lopes, S. Dash (Chalmers, Sweden), and R. Ribeiro-Palau (Paris, France)

Associate Partner (not financially supported)

• DFG SPP 2244 (2024 – 2027): Tailoring (opto)spintronic phenomena by van-der-Waals heterostructure design, PIs: H. Lv, and H. Tornatzky

2024

1. All-epitaxial Fe_5-xGeTe₂/graphene and Fe_5-xGeTe₂/WSe₂ van der Waals heterostructures with above room temperature ferromagnetism
   Authors: H. Lv, J. Herfort, M. Hanke, C. Chen, J. M. Redwing, A. Trampert, R. Engel-Herbert, M. Ramsteiner, and J. M. J. Lopes
   Published in: IEEE Trans. Magn. 60, 4100505 (2024)
   DOI: 10.1109/TMAG.2024.3426954

2023

1. Large-area synthesis of ferromagnetic Fe_5-xGeTe₂/graphene van der Waals heterostructures with Curie temperature above room temperature
   Authors: H. Lv, A. da Silva, A. I. Figueroa, C. Guillemard, I. Fernández, Aguirre, L. Camosi, L. Aballe, M. Valvidares, S. O. Valenzuela, J. Schubert, M. Schmidbauer, J. Herfort, M. Hanke, A. Trampert, R. Engel-Herbert, M. Ramsteiner, and J. M. J. Lopes
   Published in: Small, 2302387 (2023)
   DOI: 10.1002/smll.202302387
    
2. Underlying mechanisms and tunability of the anomalous Hall effect in NiCo₂O4 films with robust perpendicular magnetic anisotropy
   Authors: H. Lv, X. C. Huang, K. H. L. Zhang, O. Bierwagen, and M. Ramsteiner
   Published in: Adv. Sci. 10 2302956 (2023)
   DOI: 10.1002/advs.202302956
    
3. Resonant and Off-Resonant Magnetoacoustic Waves in Epitaxial Fe₃Si/GaAs Hybrid Structures
   Authors: M. Rovirola, M. W. Khaliq, B. Casals, M. Foerster, M. A. Niño, L. Aballe, J. Herfort, J. M. Hernàndez, F. Macià, and A. Hernández-Mínguez
   Published in: Phys. Rev. Appl. 20, 034052 (2023)
   DOI: 10.1103/PhysRevApplied.20.034052