13-19 June 2015
University of Alberta
America/Edmonton timezone
Welcome to the 2015 CAP Congress! / Bienvenue au congrès de l'ACP 2015!

Extensions of Kinetic Monte Carlo simulations to study thermally activated grain reversal in dual-layer Exchange Coupled Composite recording media.

15 Jun 2015, 16:30
15m
NINT Taylor room (University of Alberta)

NINT Taylor room

University of Alberta

Oral (Non-Student) / orale (non-étudiant) Condensed Matter and Materials Physics / Physique de la matière condensée et matériaux (DCMMP-DPMCM) M2-1 Computational methods in condensed matter physics (DCMMP) / Méthodes numériques en physique de la matière condensée (DPMCM)

Speaker

Dr Ahmad Almudallal (Memorial University of Newfoundland)

Description

Thermal activation processes represent the biggest challenge to maintain data on magnetic recording media, which is composed of uniformly magnetized nano-meter grains. These processes occur over long time scales, years or decades, and result in reversing magnetization of the media grains by rare events. Typically, rare events present a challenge if modelled by conventional micromagnetic techniques as they are limited to time scales on the order of microseconds even with the best computer resources. A convenient approach that can access long time scales and be able to simulate such rare events processes is the Kinetic Monte Carlo method (KMC). The KMC method computes the time between successive grain reversals induced by an external magnetic field based on an Arrhenius-Neel approximation for thermally activated processes. The KMC method has recently been applied to model single-layer media [1], and we have now extended the method to study dual-layer Exchange Coupled Composition (ECC) media used in current generations of disc drives. A complication to using the KMC method for ECC media is governed by the complex reversal process of coupled grains due to the existence of metastable states. The energy barrier separating the metastable states is obtained from the minimum energy path (MEP) using a variant of the nudged elastic band method [2] and the attempt frequency is calculated based on the Langer formalism [3]. To simplify carrying KMC from single layer media to a dual-layer, we have performed a detailed study for only two coupled grains to help us understand and explore the energy landscape of ECC media and be able to handle the complications associated with ECC media [4]. Applications to study characteristic MH hysteresis loops for multi-grained dual-layered systems is made. 1. M. L. Plumer, T. J. Fal, J. I. Mercer, J. P. Whitehead, J. van Ek, and A. Ajan, IEEE Trans. Mag, 50, 3100805 (2014). 2. R. Dittrich, T. Schrefl, D. Suess, W. Scholz, H. Forster and J. Fidler, R. J.M.M.M. 250, L12–L19 (2002). 3. J. S. Langer, Ann. Phys. 54 258, N.Y. (1969). 4. A. M. Almudallal, J. I. Mercer, J. P. Whitehead, M. Plumer, J. van Ek and T. J. Fal (submitted).

Primary author

Dr Ahmad Almudallal (Memorial University of Newfoundland)

Co-authors

Mr Jason Mercer (Memorial University of Newfoundland) Prof. John Whitehead (Memorial University of Newfoundland) Prof. Martin Plumer (Memorial University of Newfoundland) Dr Timothy Fal (University of Colorado at Colorado Springs)

Presentation Materials

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