@article{MiedemaThielemannKuehnCalafelletal.2019,
  author    = {Miedema, Piter S. and Thielemann-K{\"u}hn, Nele and Calafell, Irati Alonso and Sch{\"u}ßler-Langeheine, Christian and Beye, Martin},
  title     = {Strain analysis from M-edge resonant inelastic X-ray scattering of nickel oxide films},
  series = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  volume    = {21},
  journal   = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  number    = {38},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1463-9076},
  doi       = {10.1039/c9cp03593a},
  pages     = {21596 -- 21602},
  year      = {2019},
  abstract  = {Electronic structure modifications due to strain are an effective method for tailoring nano-scale functional materials. Demonstrated on nickel oxide (NiO) thin films, Resonant Inelastic X-ray Scattering (RIXS) at the transition-metal M-2,M-3-edge is shown to be a powerful tool for measuring the electronic structure modification due to strain in the near-surface region. Analyses from the M-2,M-3-edge RIXS in comparison with dedicated crystal field multiplet calculations show distortions in 40 nm NiO grown on a magnesium oxide (MgO) substrate (NiO/MgO) similar to those caused by surface relaxation of bulk NiO. The films of 20 and 10 nm NiO/MgO show slightly larger differences from bulk NiO. Quantitatively, the NiO/MgO samples all are distorted from perfect octahedral (O-h) symmetry with a tetragonal parameter Ds of about -0.1 eV, very close to the Ds distortion from octahedral (O-h) symmetry parameter of -0.11 eV obtained for the surface-near region from a bulk NiO crystal. Comparing the spectra of a 20 nm film of NiO grown on a 20 nm magnetite (Fe3O4) film on a MgO substrate (NiO/Fe3O4/MgO) with the calculated multiplet analyses, the distortion parameter Ds appears to be closer to zero, showing that the surface-near region of this templated film is less distorted from O-h symmetry than the surface-near region in bulk NiO. Finally, the potential of M-2,M-3-edge RIXS for other investigations of strain on electronic structure is discussed.},
  language  = {en}
}
@phdthesis{ThielemannKuehn2017,
  author    = {Thielemann-K{\"u}hn, Nele},
  title     = {Optically induced ferro- and antiferromagnetic dynamics in the rare-earth metal dysprosium},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-402994},
  school      = {Universit{\"a}t Potsdam},
  pages     = {iv, 121},
  year      = {2017},
  abstract  = {Approaching physical limits in speed and size of today's magnetic storage and processing technologies demands new concepts for controlling magnetization and moves researches on optically induced magnetic dynamics. Studies on photoinduced magnetization dynamics and their underlying mechanisms have been primarily performed on ferromagnetic metals. Ferromagnetic dynamics bases on transfer of the conserved angular momentum connected with atomic magnetic moments out of the parallel aligned magnetic system into other degrees of freedom. In this thesis the so far rarely studied response of antiferromagnetic order to ultra-short optical laser pulses in a metal is investigated. The experiments were performed at the FemtoSpex slicing facility at the storage ring BESSY II, an unique source for ultra-short elliptically polarized x-ray pulses. Laser-induced changes of the 4f-magnetic order parameter in ferro- and antiferromagnetic dysprosium (Dy), were studied by x-ray methods, which yield directly comparable quantities. The discovered fundamental differences in the temporal and spatial behavior of ferro- and antiferrmagnetic dynamics are assinged to an additional channel for angular momentum transfer, which reduces the antiferromagnetic order by redistributing angular momentum within the non-parallel aligned magnetic system, and hence conserves the zero net magnetization. It is shown that antiferromagnetic dynamics proceeds considerably faster and more energy-efficient than demagnetization in ferromagnets. By probing antiferromagnetic order in time and space, it is found to be affected along the whole sample depth of an in situ grown 73 nm tick Dy film. Interatomic transfer of angular momentum via fast diffusion of laser-excited 5d electrons is held responsible for the out-most long-ranging effect. Ultrafast ferromagnetic dynamics can be expected to base on the same origin, which however leads to demagnetization only in regions close to interfaces caused by super-diffusive spin transport. Dynamics due to local scattering processes of excited but less mobile electrons, occur in both magnetic alignments only in directly excited regions of the sample and on slower pisosecond timescales. The thesis provides fundamental insights into photoinduced magnetic dynamics by directly comparing ferro- and antiferromagnetic dynamics in the same material and by consideration of the laser-induced magnetic depth profile.},
  language  = {en}
}
@article{ThielemannKuehnHoffmannFoehlisch2012,
  author    = {Thielemann-K{\"u}hn, Nele and Hoffmann, P. and F{\"o}hlisch, Alexander},
  title     = {A versatile detector for total fluorescence and electron yield experiments},
  series = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  volume    = {83},
  journal   = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  number    = {9},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0034-6748},
  doi       = {10.1063/1.4754126},
  pages     = {3},
  year      = {2012},
  abstract  = {The combination of a non-coated silicon photodiode with electron repelling meshes makes a versatile detector for total fluorescence yield and electron yield techniques highly suitable for x-ray absorption spectroscopy. In particular, a copper mesh with a bias voltage allows to suppress or transmit the electron yield signal. The performance of this detection scheme has been characterized by near edge x-ray absorption fine structure studies of thermal oxidized silicon and sapphire. The results show that the new detector probes both electron yield and for a bias voltage exceeding the maximum photon energy the total fluorescence yield.},
  language  = {en}
}
@article{ThielemannKuehnSchickPontiusetal.2017,
  author    = {Thielemann-K{\"u}hn, Nele and Schick, Daniel and Pontius, Niko and Trabant, Christoph and Mitzner, Rolf and Holldack, Karsten and Zabel, Hartmut and F{\"o}hlisch, Alexander and Schuessler-Langeheine, Christian},
  title     = {Ultrafast and Energy-Efficient Quenching of Spin Order: Antiferromagnetism Beats Ferromagnetism},
  series = {Physical review letters},
  volume    = {119},
  journal   = {Physical review letters},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {0031-9007},
  doi       = {10.1103/PhysRevLett.119.197202},
  pages     = {6},
  year      = {2017},
  abstract  = {By comparing femtosecond laser pulse induced ferro- and antiferromagnetic dynamics in one and the same material-metallic dysprosium-we show both to behave fundamentally different. Antiferromagnetic order is considerably faster and much more efficiently reduced by optical excitation than its ferromagnetic counterpart. We assign the fast and extremely efficient process in the antiferromagnet to an interatomic transfer of angular momentum within the spin system. Our findings imply that this angular momentum transfer channel is effective in other magnetic metals with nonparallel spin alignment. They also point out a possible route towards energy-efficient spin manipulation for magnetic devices.},
  language  = {en}
}