Presentation Information
[10p-PB3-4]Proximity-induced magnetism of Gd in Co/Gd/CoFeB artificial ferrimagnetic trilayers studied with combinatorial XMCD spectroscopy
〇Songtian Li1, Tetsuro Ueno1, Phillip David Bentley1, Yoshiyuki Ohtsubo1, Yoshinori Kotani2, Seiji Sakai1 (1.QST, 2.JASRI)
Keywords:
XMCD,artificial ferrimagnet,all-optical switching
Rare earth/transition metal artificial ferrimagnetic multilayers are attracting increasing interest due to their high potential for realizing all-optical switching (AOS). We recently demonstrated single-pulse-triggered AOS in a newly developed artificial ferrimagnet incorporating a Co/Gd/CoFeB trilayer structures. The AOS properties in these trilayers were found to be sensitive to the layer thickness, especially that of the Gd layer, which plays a crucial role in controlling the ferrimagnetic properties and magnetic anisotropy of the trilayers. To gain a deeper understanding of Gd magnetism and its role in AOS, we conducted combinatorial X-ray magnetic circular dichroism (XMCD) spectroscopy measurements on a wedge-structured Co/Gd/CoFeB trilayer sample.
The sample was designed to contain a Gd wedge (1–5 nm). XMCD measurements were performed in total electron yield mode at the BL13U beamline of NanoTerasu. Atomic magnetic moments of Gd for different layer thicknesses were calculated from the XMCD spectra using the sum rules. The total magnetic moment was found to decrease with increasing Gd thickness. This suggests that the magnetism in Gd originates from the proximity effect at the Co/Gd and Gd/CoFeB interfaces. Noteworthy, our analysis reveals that a substantial orbital moment is induced in the Gd layer, and its magnitude decreases with increasing Gd thickness. A possible explanation is that the close proximity of transition metal 3d and Gd 5d states leads to orbital mixing and crystal field effects, quenching the spherical symmetry of the Gd 4f shell and lifting degeneracy, thereby allowing a non-zero orbital angular momentum. This finding provides a new insight on understanding the magnetism of the rare earth/transition metal multilayer systems.
The influence of proximity-induced magnetism in Gd on the antiferromagnetic coupling and the magnetic anisotropy of the trilayers and its role on AOS will be discussed in detail.
The sample was designed to contain a Gd wedge (1–5 nm). XMCD measurements were performed in total electron yield mode at the BL13U beamline of NanoTerasu. Atomic magnetic moments of Gd for different layer thicknesses were calculated from the XMCD spectra using the sum rules. The total magnetic moment was found to decrease with increasing Gd thickness. This suggests that the magnetism in Gd originates from the proximity effect at the Co/Gd and Gd/CoFeB interfaces. Noteworthy, our analysis reveals that a substantial orbital moment is induced in the Gd layer, and its magnitude decreases with increasing Gd thickness. A possible explanation is that the close proximity of transition metal 3d and Gd 5d states leads to orbital mixing and crystal field effects, quenching the spherical symmetry of the Gd 4f shell and lifting degeneracy, thereby allowing a non-zero orbital angular momentum. This finding provides a new insight on understanding the magnetism of the rare earth/transition metal multilayer systems.
The influence of proximity-induced magnetism in Gd on the antiferromagnetic coupling and the magnetic anisotropy of the trilayers and its role on AOS will be discussed in detail.