Magnetization Precession at Sub‐Terahertz Frequencies in Polycrystalline Cu2Sb‐Type (Mn–Cr)AlGe Ultrathin Films. Issue 20 (15th April 2022)

• Record Type: Journal Article
• Authors: Sasaki, Yuta; Hiramatsu, Ryoya; Kota, Yohei; Kubota, Takahide; Sonobe, Yoshiaki; Sakuma, Akimasa; Takanashi, Koki; Kasai, Shinya; Takahashi, Yukiko K.
• Is Part Of: Small. Volume 18:Issue 20(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-15
• Subjects: all‐optical methods -- perpendicular magnetic anisotropy -- terahertz spintronics -- ultrathin films; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202200378
• Languages: English
• ISSNs: 1613-6810

Abstract

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 Cu2 Sb‐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. Abstract : A ferromagnetic metal nanolayer with large perpendicular magnetic anisotropy (PMA) energy and small magnetic damping constant are crucial for high‐speed spintronic devices. In this study, sub‐terahertz magnetization dynamics with large PMA energy in Cu2 Sb‐type (Mn–Cr)AlGe films are investigated by an all‐optical method. The precession frequency of 0.164 THz with a small effective magnetic damping constant of 0.012 is obtained.