Abstract
The combination of Co, Gd, and Pt materials is a representative with perpendicular magnetic anisotropy (PMA) for the all-optical switching (AOS), which provides a promising route for ultrafast magnetization manipulation. This paper shows that the PMA of Co100−xGdx/Pt multilayers mainly originates not from the bulk property of ferrimagnetic Co100−xGdx but from the interface magnetic anisotropy between the Co100−xGdx and Pt layers. In addition, the contribution of magnetic moment induced in Pt becomes remarkable, which modulates the compensation temperature for the samples with thin Co100−xGdx layers. The Co100−xGdx/Pt multilayers exhibited the all-optical helicity-independent switching in a wide range of Gd concentrations, and the maximum AOS probability was achieved near the compensation composition. We discuss the correlation between the magnetic properties and the AOS probability for the Co100−xGdx/Pt multilayers. The AOS showed clear thickness dependence, which was attributable to the remarkable contribution of induced moment. Our findings are beneficial not only for understanding the mechanism of AOS but also for designing spintronic devices using ferrimagnets.
Highlights
Magnetization manipulation on ultrashort time scales is one of the major issues for developing high speed spintronic devices
In the actual case, the Co–Gd has probably nonuniformity, as reported in Ref. 30, which might prevent the divergence of Hani. This directly affects the evaluation of Ks, and Ks becomes small due to the small Ms The value of Kv follows the tendency of −2πMs2. These results indicate that the Co–Gd bulk contribution to the perpendicular magnetic anisotropy (PMA) is negligibly small, and the interface with the Pt layer plays the major role for obtaining PMA
The origin of PMA and the role of induced magnetic moment were investigated for the Co–Gd/Pt multilayers
Summary
Magnetization manipulation on ultrashort time scales is one of the major issues for developing high speed spintronic devices. In addition to the AOS experiment, Gd–Fe–Co and Co–Gd are promising materials for antiferromagnetic spintronics.. The elucidation of the origin of PMA in the amorphous Co–Gd is essential for the AOS study and for the spintronics research. The layer combination of Co, Gd, and Pt was used for the AOS experiment as well, e.g., Pt/Co/Gd artificial ferrimagnets.5,27 These facts make rare earth-transition metal systems a unique platform to investigate the correlation between the fundamental magnetic properties and the AOS behavior, which will provide knowledge to gain insight into the nature of AOS. The origin of PMA and the role of interface magnetic moment were examined for the multilayers consisting of amorphous Co–Gd and Pt. The magnetic properties were systematically investigated for the Co–Gd/Pt with various Co–Gd layer thicknesses (t) and alloy compositions (Co100−xGdx). The temperature dependence of the anomalous Hall effect was investigated for the microfabricated Hall crosses
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