Magnetic Decay at Elevated Temperature Relevant to Heat-Assisted Magnetic Recording

This work uses established techniques for quantifying energy barriers to thermal decay of magnetization in magnetic recording media appropriate for heat-assisted magnetic recording (HAMR). These measurements have been made as a function of temperature and examined for reasonableness, self-consistency, and their ability to predict adjacent track aging in HAMR. We find that the demagnetizing factors and energy barrier distribution widths derived from these measurements appear unreliable. However, zero-time switching fields (often designated H ₀ ) appear to be reliably determined, as are mean energy barriers. We conclude that significant magnetization rotation is the source of this unreliability and it also contributes to larger than expected distributions in H ₀ and a larger than expected temperature dependence of H ₀. Decay predictions are surprisingly effective given the limited amount of reliability in barrier width and demagnetizing field, but a model of decay that includes rotation appears to be needed.