Erasure temperature measurements of heat assisted magnetic recording media
Chen, Y. J.
Yang, H. Z.
Leong, S. H.
Cher, K. M.
Hu, J. F.
Lew, Wen Siang
Date of Issue2015
School of Physical and Mathematical Sciences
For heat assisted magnetic recording (HAMR) media development, measurement of erasure temperature (Te) is interesting and important for practical HAMR testing and applications. Here, we present an investigation on Te measurements of L10 ordered FePt granular HAMR media made using a Laser Heating (LH) method on a home-built HAMR write test system versus that from a bulk heating approach. The HAMR write test system provides HAMR writing, micro-MOKE (magneto-optical Kerr effect) signal detection, and MOKE imaging functions at the same testing spot in one single system. Magnetic force microscopy (MFM) and magnetic Kerr microscopy observations of the scanning laser induced degradation/erasure/demagnetization of the pre-recorded magnetic patterns on disk media (over a wide area of a few hundreds of μm2) show that the magnetic (MFM and Kerr signal) amplitude of the pre-recorded magnetic patterns decreases slowly with increasing laser power (Pw) (/temperature rise) for Pw ≲ 66 mW and then drops sharply to nearly zero for Pw ≥ ∼72 mW (the laser power corresponding to complete thermal erasure when the media temperature is ∼Te). It was further found that this trend of magnetic amplitude reduction with increased Pw is similar to that from magnetic amplitude decrease of pre-recorded magnetic patterns with increased bulk heating temperature. The temperature for complete erasure at laser power, Pw = 72 mW for the LH method, corresponds therefore to ∼650 K (≈Te) for the bulk heating methods. Besides fast measurement, LH (as a comparable and viable approach for erasure measurement) is dynamic, localized, and has time scales closer to practical HAMR situation.
DRNTU::Science::Physics::Electricity and magnetism
Journal of applied physics
© 2015 AIP Publishing LLC. This paper was published in Journal of Applied Physics and is made available as an electronic reprint (preprint) with permission of AIP Publishing LLC. The paper can be found at the following official DOI: [http://dx.doi.org/10.1063/1.4914362]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.