All-optical study of tunable ultrafast spin dynamics in [Co/Pd]/NiFe systems: the role of spin-twist structure on Gilbert damping
2016 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 83, 80168-80173 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
Royal Society of Chemistry, 2016. Vol. 6, no 83, 80168-80173 p.
IdentifiersURN: urn:nbn:se:kth:diva-193502DOI: 10.1039/c6ra12227bISI: 000382539600103OAI: oai:DiVA.org:kth-193502DiVA: diva2:1034101
FunderSwedish Research CouncilKnut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research EU, European Research Council, 307144
QC 201610112016-10-112016-10-032016-10-11Bibliographically approved