Growth and properties of hybrid thin film systems – Thin films and magnetic heterostructures

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PhD

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Team

• Permanent members: Yunlin Zheng, Franck Vidal, Marcel Hennes, Dominique Demaille
• PhD students: Carlos Cortéz, Moundji Hemili (iMAT scholarship, co-supervision LCPMR)

Increasing the information density of magnetic storage media requires to look for new synthesis strategies yielding magnetic nano-objects and thin films with adjustable magnetic properties. Our research activities focus on the growth and structural properties of self-assembled, vertically epitaxied ferromagnetic nanowires (diameter < 10 nm), of ferro- and ferrimagnetic alloy and oxide thin films. We use these structures as model systems to study magnetic properties at the nanoscale, with special emphasis on magnetic anisotropy control (via strain, concentration or temperature), as well as (ultrafast) magnetization dynamics.

Research topics :

• alloy nanowire growth (CoNi, CoPt), anisotropy control and magnetoplasmonic properties (Au/CoNi),
• coupling of magnetic and photostrictive properties (ANR HYPNOSE),
• growth and characterization of rare earth – transition metal thin films (CoTb, FeTb),
• structural and magnetic properties of epitaxial oxide thin films.

Figure 1 : a) Nanowire growth using pulsed laser deposition. b) Self-assembled ferromagnetic nanowires and anisotropy control, c) magnetic hysteresis measured in plane (red) and out of plane (blue). d) Magnetic domains in CoTb thin films with large out-of-plane anisotropy (20 μm x 20 μm), e) modification of the magnetic texture in an external magnetic field (200 mT).

Collaborations 

• SOLEIL (beamlines: SAMBA, DEIMOS et SixS)
• C2N
• GEMaC
• LCPMR
• LOA
• IMPMC

Recent publications

• X. Weng, M. Hennes, A. Juhin, P. Sainctavit, B. Gobaut, E. Otero, F. Choueikani, P. Ohresser, T. Tran, D. Hrabovsky, D. Demaille, Y. Zheng, F. Vidal, Strain-engineering of magnetic anisotropy in Co_xNi_1−x-SrTiO₃/SrTiO₃(001) vertically assembled nanocomposites. Physical Review Materials 6, 046001 (2022) https://hal.science/hal-03635027/document
• M. Hennes, D. Demaille, G. Patriarche, T. Tran, Y. Zheng, F. Vidal, Strain, magnetic anisotropy, and composition modulation in hybrid metal-oxide vertically assembled nanocomposites. MRS Bulletin 46, 136141 (2021) invited https://hal.science/hal-03190529/document
• M. Hennes, X.Weng, E. Fonda, B. Gallas, G. Patriarche, D. Demaille, Y. Zheng, F. Vidal. Phase separation and surface segregation in Co-Au-SrTiO₃ thin films : Self-assembly of bilayered epitaxial nanocolumnar composites.  Physical Review Materials 3, 035002 (2019) https://hal.archives-ouvertes.fr/hal-02088684
• G. Radtke, M. Hennes, M. Bugnet, Q. Ramasse, X. Weng, D. Demaille, B. Gobaut, P. Ohresser, E. Otero, F. Choueikani, A. Juhin, Ph. Sainctavit, Y. Zheng, F. Vidal. Atomic-Scale Study of Metal-Oxide Interfaces and Magnetoelastic Coupling in Self-Assembled Epitaxial Vertically Aligned Magnetic Nanocomposites, Advanced Materials Interfaces 6, 1900549 (2019) https://hal.archives-ouvertes.fr/hal-02188798
  
• X. Weng, M. Hennes, A. Coati, A. Vlad, Y. Garreau, M. Sauvage-Simkin, E. Fonda, G. Patriarche, D. Demaille, F. Vidal, Y. Zheng. Ultrathin Ni nanowires embedded in SrTiO₃ : Vertical epitaxy, strain relaxation mechanisms, and solid-state amorphization. Physical Review Materials 2, 106003 (2018) https://hal.archives-ouvertes.fr/hal-01901688.