Work

Enhancement of damping constant in Nd-doped L10-FePt at elevated temperatures for HAMR

Year: 2026

Type: article

Abstract: Hard disk drives (HDDs) are main storage devices in data centers handling petabyte-scale AI data, and achieving higher recording density with heat-assisted magnetic recording (HAMR) requires media material design that ensures a sufficiently large damping constant ( α ) at elevated temperatures to enable reliable magnetization reversal. We investigated Nd-doped L1 0 -FePt continuous films to clarify the effect of rare-earth element doping on α at elevated temperatures where recording occurs. (FePt) 100-x (Nd) x thin films with Nd content ranging from 0.0 to 4.1 at.% were prepared by sputtering and characterized for microstructure and magnetic properties. Nd was completely rejected from FePt, and Nd and Pt segregated into Fe-deficient void regions in the FePt layer. Nevertheless, enhanced spin-orbit coupling (SOC) locally at the FePt/Nd interface increased magnetic anisotropy with a small amount of Nd doping. The magnetization dynamics were measured by time-resolved magneto-optical Kerr effect (TRMOKE) from room temperature to near T C . Effective α near T C increased from 0.048 (undoped) to 0.066 (Nd 4.1 at.%). These findings demonstrate that rare-earth element doping can modulate α even in FePt, which already exhibits strong SOC, and highlight a media design strategy to optimize α for HAMR performance.

Source: Acta Materialia

DOI: 10.1016/j.actamat.2026.122826

Authors: Aiko Sakoguchi, Yuta Sasaki, Daisuke Ogawa, Jun Uzuhashi, Hirofumi Suto, Yukiko K. Takahashi