In heat-assisted magnetic recording (HAMR), a laser is employed above the read-write transducer to provide energy to the media, lowering its coercivity. However, the laser also brings thermal energy diffusion inside the slider and induces an extra angstrom-level protrusion, which we call laser-induced protrusion (LIP). The LIP needs to be taken into consideration in HAMR due to the significance of head-media spacing. This paper focuses on laser heating on the millisecond timescale during flying in the HAMR conditions. When the laser is turned ON for milliseconds, the LIP forms in the short term ( ∼ μs) and fly height change (FHC) happens in the long term (∼ ms) due to the crown/camber change, resulting in a smaller touchdown power (TDP). Thus, the touchdown power change (ΔTDP) is measured and the LIP is isolated using the time constants. A component-level HAMR stage is used to study the effects of laser-on time, laser current, and linear velocity on the ΔTDP. The experimental results show that the FHC needs ∼ 28 ms to reach the steady state and that the protrusion size presents a two-stage linear relation with the laser current separated by a threshold. The LIP size is reduced by about half when operating from 12 m/s to 24 m/s.

中文翻译：

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在热辅助磁记录中使用触地测量埃级激光诱导突起

在热辅助磁记录 (HAMR) 中，在读写换能器上方采用激光器为介质提供能量，从而降低其矫顽力。然而，激光也会在滑块内部带来热能扩散，并导致额外的埃级突起，我们称之为激光诱导突起 (LIP)。由于头部介质间距的重要性，在 HAMR 中需要考虑 LIP。本文重点研究在 HAMR 条件下飞行过程中毫秒级的激光加热。当激光打开几毫秒时，由于冠度/弧度变化，LIP 会在短期 (∼ μs) 内形成，飞行高度变化 (FHC) 会在长期 (∼ ms) 内发生，从而导致更小的触地功率(TDP)。因此，测量着陆功率变化 (ΔTDP) 并使用时间常数隔离 LIP。组件级 HAMR 平台用于研究激光开启时间、激光电流和线速度对 ΔTDP 的影响。实验结果表明，FHC 需要约 28 ms 才能达到稳态，并且突起尺寸与被阈值隔开的激光电流呈两级线性关系。当从 12 m/s 运行到 24 m/s 时，LIP 尺寸减少了大约一半。