Non-equilibrium heating path for utrafast laser-induced nucleation of skyrmion lattices
Authors:
Pablo Olleros-Rodríguez,
Mara S. Strungaru,
Sergiu I. Ruta,
Paul I. Gavriloaea,
Paolo Perna,
Roy W. Chantrell,
Oksana Chubykalo-Fesenko
Abstract:
We explore the helicity-independent light-induced nucleation of skyrmion lattices in ferromagnetic cobalt-based trilayers with perpendicular magnetic anisotropy. Using Atomistic Spin Dynamics simulations, we show that a high temperature excitation followed by magnon drops and their non-equilibrium relaxation, accessed by an ultrafast laser excitation with specific duration and intensity, can lead…
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We explore the helicity-independent light-induced nucleation of skyrmion lattices in ferromagnetic cobalt-based trilayers with perpendicular magnetic anisotropy. Using Atomistic Spin Dynamics simulations, we show that a high temperature excitation followed by magnon drops and their non-equilibrium relaxation, accessed by an ultrafast laser excitation with specific duration and intensity, can lead to the generation of a skyrmion lattice stable at room temperature. The nucleation window, the topological density and the skyrmion polarity can be additionally manipulated by external magnetic fields. Our results provide insight into the non-equilibrium nature of skyrmionic excitations at non-zero temperatures and pave additional routes for their use in information technologies.
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Submitted 17 November, 2020; v1 submitted 11 November, 2020;
originally announced November 2020.
Magnetisation dynamics of granular HAMR media by means of a multiscale model
Authors:
Andrea Meo,
Wasan Pantasri,
Wassana Daeng-am,
Samuel E. Rannala,
Sergiu I. Ruta,
Roy W. Chantrell,
Phanwadee Chureemart,
Jessada Chureemart
Abstract:
Heat assisted magnetic recording (HAMR) technology represents the most promising candidate to replace the current perpendicular recording paradigm to achieve higher storage densities. To better understand HAMR dynamics in granular media we need to describe accurately the magnetisation dynamics up to temperatures close to the Curie point. To this end we propose a multiscale approach based on the mi…
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Heat assisted magnetic recording (HAMR) technology represents the most promising candidate to replace the current perpendicular recording paradigm to achieve higher storage densities. To better understand HAMR dynamics in granular media we need to describe accurately the magnetisation dynamics up to temperatures close to the Curie point. To this end we propose a multiscale approach based on the micromagnetic Landau-Lifshitz-Bloch (LLB) equation of motion parametrised using atomistic calculations. The LLB formalism describes the magnetisation dynamics at finite temperature and allows to efficiently simulate large system sizes and long time scales. Atomistic simulations provide the required temperature dependent input quantities for the LLB equation, such as the equilibrium magnetisation and the anisotropy, and can be used to capture the detailed magnetisation dynamics. The multiscale approach makes possible to overcome the computational limitations of atomistic models in dealing with large systems, such as a recording track, while incorporating the basic physics of the HAMR process. We investigate the magnetisation dynamics of a single FePt grain as function of the properties of the temperature profile and applied field and test the micromagnetic results against atomistic calculations. Our results prove the appropriateness and potential of the approach proposed here where the granular model is able to reproduce the atomistic simulations and capture the main properties of a HAMR medium.
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Submitted 28 April, 2020;
originally announced April 2020.