SPICE Workshop on Nanomagnetism in 3D, April 30th - May 2nd 2024
Joo-Von Kim
Titiksha Srivastava (1,2), Grégoire de Loubens (1), and Joo-Von Kim (2)
1. SPEC, CEA, CNRS, Univ. Paris-Saclay, 91190 Gif-sur-Yvette, France
2. Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay, 91120 Palaiseau, France
Skyrmion lattices are present in many different chiral magnetic systems and their existence derives from a number of competing interactions. In a recent work [1], we showed that Pt/FeCoB/Al2O3 multilayers can host lattices of three-dimensional skyrmionic textures over a range of applied perpendicular fields. A particular feature of this material system is the presence of a “high-frequency” mode (HFM) under transverse field pumping, in the range of 12-18 GHz, which involves the coherent precession of the skyrmion cores and results in the generation of spin waves that flow into the uniform background region between skyrmions. Here, we discuss the results of micromagnetics simulations where we examine the role of spin wave interactions with the 3D skyrmion cores. As the applied field increases and skyrmions begin to annihilate, leaving vacancies in the hexagonal lattice, the excitation of the HFM can serve to “anneal” the lattice, resulting in a glassy state. Spin wave interactions are found to provide a dynamical repulsive force between the skyrmion cores, which result in a more homogeneous arrangement in terms of density, but at the expense of crystalline order. These results also shed new light on how dynamical excitations can influence phase transitions associated with the melting of skyrmion lattices [2].
This work was partially supported by the Agence Nationale de la Recherche under contract no. ANR-17-CE24-0025 (TOPSKY) and the Horizon2020 Framework Programme of the European Commission under contract no. 899646 (k-Net).
[1] T. Srivastava et al, APL Mater. 11, 061110 (2023).
[2] P. Huang et al, Nat. Nanotechnol., vol. 15, 761 (2020).