@article{KocReinhardtvonReppertetal.2017,
  author    = {Koc, A. and Reinhardt, M. and von Reppert, Alexander and R{\"o}ssle, Matthias and Leitenberger, Wolfram and Gleich, M. and Weinelt, M. and Zamponi, Flavio and Bargheer, Matias},
  title     = {Grueneisen-approach for the experimental determination of transient spin and phonon energies from ultrafast x-ray diffraction data: gadolinium},
  series = {Journal of physics : Condensed matter},
  volume    = {29},
  journal   = {Journal of physics : Condensed matter},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0953-8984},
  doi       = {10.1088/1361-648X/aa7187},
  pages     = {5884 -- 5891},
  year      = {2017},
  abstract  = {We study gadolinium thin films as a model system for ferromagnets with negative thermal expansion. Ultrashort laser pulses heat up the electronic subsystem and we follow the transient strain via ultrafast x-ray diffraction. In terms of a simple Grueneisen approach, the strain is decomposed into two contributions proportional to the thermal energy of spin and phonon subsystems. Our analysis reveals that upon femtosecond laser excitation, phonons and spins can be driven out of thermal equilibrium for several nanoseconds.},
  language  = {en}
}
@article{MatternPudellDumesniletal.2023,
  author    = {Mattern, Maximilian and Pudell, Jan-Etienne and Dumesnil, Karine and von Reppert, Alexander and Bargheer, Matias},
  title     = {Towards shaping picosecond strain pulses via magnetostrictive transducers},
  series = {Photoacoustics},
  volume    = {30},
  journal   = {Photoacoustics},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {2213-5979},
  doi       = {10.1016/j.pacs.2023.100463},
  pages     = {7},
  year      = {2023},
  abstract  = {Using time-resolved x-ray diffraction, we demonstrate the manipulation of the picosecond strain response of a metallic heterostructure consisting of a dysprosium (Dy) transducer and a niobium (Nb) detection layer by an external magnetic field. We utilize the first-order ferromagnetic-antiferromagnetic phase transition of the Dy layer, which provides an additional large contractive stress upon laser excitation compared to its zerofield response. This enhances the laser-induced contraction of the transducer and changes the shape of the picosecond strain pulses driven in Dy and detected within the buried Nb layer. Based on our experiment with rare-earth metals we discuss required properties for functional transducers, which may allow for novel field-control of the emitted picosecond strain pulses.},
  language  = {en}
}
@misc{MatternPudellDumesniletal.2023,
  author    = {Mattern, Maximilian and Pudell, Jan-Etienne and Dumesnil, Karine and von Reppert, Alexander and Bargheer, Matias},
  title     = {Towards shaping picosecond strain pulses via magnetostrictive transducers},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1321},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-58886},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-588868},
  pages     = {7},
  year      = {2023},
  abstract  = {Using time-resolved x-ray diffraction, we demonstrate the manipulation of the picosecond strain response of a metallic heterostructure consisting of a dysprosium (Dy) transducer and a niobium (Nb) detection layer by an external magnetic field. We utilize the first-order ferromagnetic-antiferromagnetic phase transition of the Dy layer, which provides an additional large contractive stress upon laser excitation compared to its zerofield response. This enhances the laser-induced contraction of the transducer and changes the shape of the picosecond strain pulses driven in Dy and detected within the buried Nb layer. Based on our experiment with rare-earth metals we discuss required properties for functional transducers, which may allow for novel field-control of the emitted picosecond strain pulses.},
  language  = {en}
}
@phdthesis{Koc2018,
  author    = {Ko{\c{c}}, Azize},
  title     = {Ultrafast x-ray studies on the non-equilibrium of the magnetic and phononic system in heavy rare-earths},
  doi       = {10.25932/publishup-42328},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-423282},
  school      = {Universit{\"a}t Potsdam},
  pages     = {ii, 117},
  year      = {2018},
  abstract  = {In this dissertation the lattice and the magnetic recovery dynamics of the two heavy rare-earth metals Dy and Gd after femtosecond photoexcitation are described. For the investigations, thin films of Dy and Gd were measured at low temperatures in the antiferromagnetic phase of Dy and close to room temperature in the ferromagnetic phase of Gd. Two different optical pump-x-ray probe techniques were employed: Ultrafast x-ray diffraction with hard x-rays (UXRD) yields the structural response of heavy rare-earth metals and resonant soft (elastic) x-ray diffraction (RSXD), which allows measuring directly changes in the helical antiferromagnetic order of Dy. The combination of both techniques enables to study the complex interaction between the magnetic and the phononic subsystems.},
  language  = {en}
}