All-optical study of tunable ultrafast spin dynamics in [Co/Pd]/NiFe systems: the role of spin-twist structure on Gilbert damping. Issue 83 (23rd August 2016)

• Record Type: Journal Article
• Authors: Banerjee, Chandrima; Pal, Semanti; Ahlberg, Martina; Nguyen, T. N. Anh; Åkerman, Johan; Barman, Anjan
• Is Part Of: RSC advances. Volume 6:Issue 83(2016)
• Page Start: 80168
• Page End: 80173
• Publication Date: 2016-08-23
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra12227b
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The competing magnetic anisotropies and the interfacial properties are found to control the static spin configuration and ultrafast demagnetization, magnetization precession and damping in [Co/Pd]/NiFe( t ) exchange spring samples. Abstract : We investigate optically induced ultrafast magnetization dynamics in [Co(0.5 nm)/Pd(1 nm)]5 /NiFe( t ) exchange-spring samples with tilted perpendicular magnetic anisotropy using a time-resolved magneto-optical Kerr effect magnetometer. The competition between the out-of-plane anisotropy of the hard layer, the in-plane anisotropy of the soft layer and the applied bias field reorganizes the spins in the soft layer, which are modified further with the variation in t . The spin-wave spectrum, the ultrafast demagnetization time, and the extracted damping coefficients – all depend on the spin distribution in the soft layer, while the latter two also depend on the spin–orbit coupling between the Co and Pd layers. The spin-wave spectra change from multimode to single-mode as t decreases. At the maximum field reached in this study, H = 2.5 kOe, the damping shows a nonmonotonic dependence on t with a minimum at t = 7.5 nm. For t < 7.5 nm, intrinsic effects dominate, whereas for t > 7.5 nm, extrinsic effects govern the damping mechanisms.