Calculating thermal stability and attempt frequency of advanced recording structures without free parameters

Abstract

Ensuring a permanent increase of magnetic storage densities is one of the main challenges in magnetic recording. Conventional approaches based on single phase grains are not suitable to achieve this goal, because their grain volume is limited due to the superparamagnetic limit. Grains with graded anisotropy are the most promising candidates to overcome this limit, providing magnetic memory bits with small volumes, low coercivity and high thermal stability at the same time. Combining micromagnetic simulations with forward flux sampling (FFS), a computational method for rare events that has been recently applied to the magnetic nanostructures, we have determined thermal escape rates and attempt frequencies of a graded media grain and two single phase grains of the same geometry. We find that graded anisotropy can increase the thermal stability of a grain by 12 orders of magnitudes from tens of milliseconds to centuries without changing the coercive field.

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Cited by in corpus (5)

• Studying Rare Events using Forward-Flux Sampling: Recent Breakthroughs and Future Outlook
• Entropy-reduced retention times in magnetic memory elements: A case of the Meyer-Neldel Compensation Rule
• Path sampling for lifetimes of metastable magnetic skyrmions and direct comparison with Kramers' method
• Quantifying the thermal stability in perpendicularly magnetized ferromagnetic nanodisks with forward flux sampling
• Single-stage direct Langevin dynamic simulations of transitions over arbitrary high energy barriers: Concept of the energy-dependent temperature