Stochastic ferrimagnetic Landau-Lifshitz-Bloch equation for finite magnetic structures

Abstract

Precise modeling of the magnetization dynamics of nanoparticles with finite size effects at fast varying temperatures is a computationally challenging task. Based on the Landau-Lifshitz-Bloch (LLB) equation we derive a coarse grained model for disordered ferrimagnets, which is both fast and accurate. First, we incorporate stochastic fluctuations to the existing ferrimagnetic LLB equation. Further, we derive a thermodynamic expression for the temperature dependent susceptibilities, which is essential to model finite size effects. Together with the zero field equilibrium magnetization the susceptibilities are used in the stochastic ferrimagnetic LLB to simulate a $5\times 10$ nm${}^2$ ferrimagnetic GdFeCo particle with 70 % FeCo and 30 % Gd under various external applied fields and heat pulses. The obtained trajectories agree well with those of an atomistic model, which solves the stochastic Landau-Lifshitz-Gilbert equation for each atom. Additionally, we derive an expression for the intergrain exchange field which couple the ferromagnetic sublattices of a ferrimagnet. A comparison of the magnetization dynamics obtained from this simpler model with those of the ferrimagnetic LLB equation shows a perfect agreement.

References in corpus (19)

• Atomistic spin model simulations of magnetic nanomaterials
• Fokker-Planck and Landau-Lifshitz-Bloch Equations for Classical Ferromagnets
• Anomalous current-induced spin torques in ferrimagnets near compensation
• Light-induced magnetization reversal of high-anisotropy TbCo alloy films
• Two types of all-optical magnetization switching mechanisms using femtosecond laser pulses
• Spin-Orbit Torques in ferrimagnetic GdFeCo Alloys
• Spin Hall Switching of the Magnetization in Ta/TbFeCo Structures with Bulk Perpendicular Anisotropy
• Two magnon bound state causes ultrafast thermally induced magnetisation switching
• Thickness Dependence of Spin-Orbit Torques in Ferrimagnetic GdFeCo Alloys
• The Landau-Lifshitz-Bloch equation for ferrimagnetic materials
• Ultrafast thermally induced magnetic switching in synthetic ferrimagnets
• Heat assisted magnetic recording of bit patterned media beyond 10 Tb/in${}^2$
• Ultrafast dynamical path for the switching of a ferrimagnet after femtosecond heating
• Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys
• Controlling the Polarity of the Transient Ferromagnetic-Like State in Ferrimagnets
• Landau-Lifshitz-Bloch equation for exchange coupled grains
• AC noise reduction based on exchange coupled grains for heat-assisted-magnetic recording: The effect of an FeRh interlayer
• Efficiently reducing transition curvature in heat-assisted magnetic recording with state-of-the-art write heads
• Influence of grain size and exchange interaction on the LLB modeling procedure

Cited by in corpus (5)

• A review of modelling in ferrimagnetic spintronics
• Emergence of Transient Domain Wall Skyrmions after Ultrafast Demagnetisation
• Universal criteria for single femtosecond pulse ultrafast magnetization switching in ferrimagnets
• The Landau-Lifshitz-Bloch equation for domain wall motion in antiferromagnets
• Realistic micromagnetic description of all-optical ultrafast switching processes in ferrimagnetic alloys