期刊
NEW JOURNAL OF PHYSICS
卷 21, 期 12, 页码 -出版社
IOP Publishing Ltd
DOI: 10.1088/1367-2630/ab5ac2
关键词
photo-induced magnetization dynamics; time-resolved XMCD; XFEL
资金
- Toray Science and Technology Grant of Toray Research Foundation
- MEXT Quantum Leap Flagship Program (MEXTQ-LEAP) [JPMXS0118068681]
- JSPS KAKENHI [19H05824, 19H01816, 17K14334, 17H02823]
- Swedish Research Council (VR)
- K and A Wallenberg Foundation [2015.0060]
- Czech Science Foundation [18-07172S]
- ALPS program of the University of Tokyo
- Grants-in-Aid for Scientific Research [19H01816, 17K14334, 17H02823] Funding Source: KAKEN
Unraveling the origin of ultrafast demagnetization in multisublattice ferromagnetic materials requires femtosecond x-ray techniques to trace the magnetic moment dynamics on individual elements, but this could not yet be achieved in the hard x-ray regime. We demonstrate here the first ultrafast demagnetization dynamics in the ferromagnetic heavy 5d-transition metal Pt using circularly-polarized hard x-rays at an x-ray free electron laser (XFEL). The decay time of laser-induced demagnetization of L1(0)-FePt is determined to be tau(Pt) = 0.61 +/- 0.04 ps using time-resolved x-ray magnetic circular dichroism at the Pt L-3 edge, whereas magneto-optical Kerr measurements indicate the decay time for the total magnetization as tau(total) < 0.1 ps. A transient magnetic state with a photomodulated ratio of the 3d and 5d magnetic moments is demonstrated for pump-probe delays larger than 1 ps. We explain this distinct photo-modulated transient magnetic state by the induced-moment behavior of the Pt atom and the x-ray probing depth. Our findings pave the way for the future use of XFELs to disentangle atomic spin dynamics contributions.
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