TY  - JOUR
A1  - Schick, Daniel
A1  - Le Guyader, Loic
A1  - Pontius, Niko
A1  - Radu, Ilie
A1  - Kachel, Torsten
A1  - Mitzner, Rolf
A1  - Zeschke, Thomas
A1  - Schuessler-Langeheine, Christian
A1  - Föhlisch, Alexander
A1  - Holldack, Karsten
T1  - Analysis of the halo background in femtosecond slicing experiments
JF  - Journal of synchrotron radiation
N2  - The slicing facility FemtoSpeX at BESSY II offers unique opportunities to study photo-induced dynamics on femtosecond time scales by means of X-ray magnetic circular dichroism, resonant and non-resonant X-ray diffraction, and X-ray absorption spectroscopy experiments in the soft X-ray regime. Besides femtosecond X-ray pulses, slicing sources inherently also produce a so-called `halo' background with a different time structure, polarization and pointing. Here a detailed experimental characterization of the halo radiation is presented, and a method is demonstrated for its correct and unambiguous removal from femtosecond time-resolved data using a special laser triggering scheme as well as analytical models. Examples are given for time-resolved measurements with corresponding halo correction, and errors of the relevant physical quantities caused by either neglecting or by applying a simplified model to describe this background are estimated.
KW  - femtosecond slicing
KW  - halo
KW  - pump-probe
KW  - XMCD
KW  - X-ray scattering
Y1  - 2016
U6  - https://doi.org/10.1107/S160057751600401X
SN  - 1600-5775
VL  - 23
SP  - 700
EP  - 711
PB  - International Union of Crystallography
CY  - Chester
ER  - 
TY  - JOUR
A1  - Rettig, L.
A1  - Dornes, C.
A1  - Thielemann-Kuehn, Nele
A1  - Pontius, N.
A1  - Zabel, Hartmut
A1  - Schlagel, D. L.
A1  - Lograsso, T. A.
A1  - Chollet, M.
A1  - Robert, A.
A1  - Sikorski, M.
A1  - Song, S.
A1  - Glownia, J. M.
A1  - Schuessler-Langeheine, Christian
A1  - Johnson, S. L.
A1  - Staub, U.
T1  - Itinerant and Localized Magnetization Dynamics in Antiferromagnetic Ho
JF  - Physical review letters
N2  - Using femtosecond time-resolved resonant magnetic x-ray diffraction at the Ho L-3 absorption edge, we investigate the demagnetization dynamics in antiferromagnetically ordered metallic Ho after femtosecond optical excitation. Tuning the x-ray energy to the electric dipole (E1, 2p -> 5d) or quadrupole (E2, 2p -> 4f) transition allows us to selectively and independently study the spin dynamics of the itinerant 5d and localized 4f electronic subsystems via the suppression of the magnetic (2 1 3-tau) satellite peak. We find demagnetization time scales very similar to ferromagnetic 4f systems, suggesting that the loss of magnetic order occurs via a similar spin-flip process in both cases. The simultaneous demagnetization of both subsystems demonstrates strong intra-atomic 4f-5d exchange coupling. In addition, an ultrafast lattice contraction due to the release of magneto-striction leads to a transient shift of the magnetic satellite peak.
Y1  - 2016
U6  - https://doi.org/10.1103/PhysRevLett.116.257202
SN  - 0031-9007
SN  - 1079-7114
VL  - 116
SP  - 6382
EP  - 6389
PB  - American Physical Society
CY  - College Park
ER  -