Manifestation of higher-order inter-granular exchange in magnetic recording media
arXiv:1706.05188 · doi:10.1063/1.4990604
Abstract
Exchange coupling between magnetic grains is essential for maintaining the stability of stored information in magnetic recording media. Using an atomistic spin model, we have investigated the coupling between neighbouring magnetic grains where magnetic impurity atoms have migrated into the non-magnetic grain boundary. We find that when the impurity density is low a biquadratic term in addition to the bilinear term is required to properly describe the inter-granular exchange coupling. The temperature dependence both terms is found to follow a power law behaviour with the biquadratic exchange constant decaying faster than the bilinear. For increasing grain boundary thickness the inter-granular exchange is lower and decays faster with temperature. Further simulations of a grain at a bit boundary show an unexpected energy minimum for in-plane magnetisation which can only be reproduced using a biquadratic exchange term.
arXiv comment4 pages, 4 figures. The following article has been submitted to Applied Physics Letters
References in corpus (4)
- Atomistic spin model simulations of magnetic nanomaterials
- Constrained Monte Carlo Method and Calculation of the Temperature Dependence of Magnetic Anisotropy
- Higher order exchange interactions leading to metamagnetism in FeRh
- Atomistic calculation of the thickness and temperature dependence of exchange coupling through a dilute magnetic oxide