Magnetization Precession at Sub-Terahertz Frequencies in Polycrystalline Cu2Sb-Type (Mn–Cr)AlGe Ultrathin Films

Yuta Sasaki*, Ryoya Hiramatsu, Yohei Kota, Takahide Kubota, Yoshiaki Sonobe, Akimasa Sakuma, Koki Takanashi, Shinya Kasai, Yukiko K. Takahashi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A ferromagnetic metal nanolayer with a large perpendicular magnetic anisotropy, small saturation magnetization, and small magnetic damping constant is a crucial requirement for high-speed spintronic devices. Fabrication of these devices on Si/SiO2 amorphous substrates with polycrystalline structure is also strongly desired for the mass production industry. This study involves the investigation of sub-terahertz (THz) magnetization precessional motion in a newly developed material system consisting of Cu2Sb-type MnAlGe and (Mn–Cr)AlGe films by means of an all-optical pump-probe method. These materials exhibit large perpendicular magnetic anisotropy in regions of a few nanometers in size. The pseudo-2D crystal structures are clearly observed in the high-resolution transmission electron microscopy (TEM) images for the film samples grown on thermally oxidized silicon substrates. The TEM images also show a partial substitution of Cr atoms for the Mn sites in MnAlGe. A magnetization precession frequency of 0.164 THz with a relatively small effective magnetic damping constant of 0.012 is obtained for (Mn–Cr)AlGe. Theoretical calculation infers that the modification of the total density of states by Cr substitution decreases the intrinsic magnetic damping constant of (Mn–Cr)AlGe.

Original languageEnglish
Article number2200378
JournalSmall
Volume18
Issue number20
DOIs
Publication statusPublished - 2022 May 19
Externally publishedYes

Keywords

  • all-optical methods
  • perpendicular magnetic anisotropy
  • terahertz spintronics
  • ultrathin films

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Chemistry(all)
  • Materials Science(all)

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