Effects of Skew Angle and Transition Curvature in HAMR Hard Disk Drives

Abstract

Continued areal density growth in hard disk drives (HDD) is becoming increasingly difficult to achieve as Perpendicular Magnetic Recording (PMR) approaches the super paramagnetic limit of ~1Tb/in2. Heat-Assisted Magnetic Recording (HAMR) is on the verge of becoming the next generation of high-density recording technology. Understanding the physical mechanisms behind the unique recording characteristics will be a critical step in the maturity of HAMR technology as it continues to make progress towards production. A notable difference between HAMR and PMR that has drawn a lot of recent attention is the curved shape of a recorded transition. Minimizing transition curvature is understood to be crucial for improving ADC, and current studies have shown that it could be imposing a significant limitation for HAMR. Here, we provide a comparison of HAMR and PMR ADC profiles in an HDD. We explore a new technique proposed for capturing magnetization footprint images through HDD testing, and take full advantage of a significantly improved cycle time to apply a statistical treatment to experimental curvature data to provide a quantitative analysis of factors that impact transition curvature in HAMR and PMR HDDs. We identify geometric effects resulting from skew angle that correlate well to changes in transition curvature. We also show the impact of laser power on transition curvature, and discuss how an understanding of this information can be used to quickly identify uncontrolled variables in an experiment.