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Hard disk drives (HDDs) remain the primary large-capacity storage solution for data centers handling petabyte-scale AI data. Heat-assisted magnetic recording (HAMR) enables higher recording density by heating the recording layer near its Curie temperature (Tc) during writing. A sufficiently large Gilbert damping constant (α) at elevated temperatures is critical to suppress thermally driven back-switching and improve recording reliability.
This study investigates Nd-doped L1₀-FePt continuous thin films with Nd content ranging from 0.0 to 4.1 at.%. Microstructural analysis by XRD, STEM, and APT revealed that Nd is completely rejected from the FePt lattice and instead segregates into Fe-deficient void regions. Despite this, small amounts of Nd doping enhanced the anisotropy field (μ₀Hk), attributed to localized spin-orbit coupling (SOC) enhancement at FePt/Nd interfaces.
Magnetization dynamics measured by TRMOKE from room temperature to near Tc showed that effective α near Tc increased from 0.048 (undoped) to 0.066 (4.1 at.% Nd), providing the first experimental demonstration of α enhancement through rare-earth doping in FePt. This enhancement is attributed to interfacial SOC effects, consistent with mechanisms reported in NiFe/rare-earth bilayer systems. These findings demonstrate that rare-earth doping can effectively modulate α in FePt-based HAMR media.

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• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International
  

Keyword: FePt, Hard disk drives, Time resolved magneto optical Kerr effect, magnetization dynamics, perpendicular magnetic anisotropy, Heat-assisted magnetic recording

Date published: 2026-09-29

Publisher: Elsevier BV

Journal:

• ACTA MATERIALIA (ISSN: 13596454) vol. 321 122826

Funding:

• Government of Japan Ministry of Education Culture Sports Science and Technology JPMXS0320230032
• Japan Society for the Promotion of Science 26K21737
• Advanced Storage Research Consortium
• Japan Science and Technology Agency JPMJCR22C3

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1016/j.actamat.2026.122826

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Updated at: 2026-10-09 13:07:09 +0900

Published on MDR: 2026-10-09 14:30:58 +0900