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@INPROCEEDINGS{Ptter:943368,
      author       = {Pütter, Sabine and Guasco, Laura and Khaydukov, Yury and
                      Silvi, Luca and Paulin, Mariano and Keller, Thomas and
                      Keimer, Bernhard},
      title        = {{D}etection of hydrogen in thin films through resonant
                      neutron reflectometry via a magnetic layer},
      reportid     = {FZJ-2023-00967},
      year         = {2023},
      abstract     = {The study of hydrogen diffusion and storage in different
                      materials is crucial in the challenge of an actual
                      implementation of sustainable energy sources, but also to
                      explore the possible modification of electronic, magnetic
                      and optical properties of the host material. Amongst the
                      most widely used techniques to study hydrogen absorption in
                      thin films are neutron (NR) and X-ray reflectometry (XRR).
                      XRR allows to track the thickness changes of the absorbing
                      layer, while NR gives in addition direct information about
                      the absorbed hydrogen content. Nonetheless, NR is a
                      relatively time-consuming measurement, with a sensitivity
                      limit that greatly depends on the counting time. The
                      detection limit is at about $5\%$ atomic concentration.In
                      this contribution we propose to apply resonant neutron
                      reflectometry (RNR) [1]. The method is model-free and allows
                      to measure smaller $(<5\%)$ concentrations of hydrogen
                      absorbed in situ, with smaller counting times and with a
                      higher sensitivity. Inserting a magnetic layer into the
                      hydrogen absorbing layer a magnetic wave guide for neutrons
                      is formed. On hydrogen loading the scattering potential of
                      the system is modified which is seen in the position of the
                      resonance formed due to the contrast between the scattering
                      potential of the absorbing layer and its neighbours. The
                      requirements for the magnetic thin film and the absorbing
                      layer are discussed. We will present experiments performed
                      on Al2O3/Nb(x)/Co(3nm)/Nb(x)/Pt(3nm) thin films
                      demonstrating that hydrogen concentrations below $1\%$ and
                      absorption kinetics of few seconds can be measured using
                      this method.Furthermore by combining information given by in
                      situ XRR and RNR performed at NREX, a neutron reflectometer
                      at the Heinz Maier-Leibnitz Zentrum in Garching, Germany we
                      were able to observe peculiarities in the absorption process
                      of niobium. In this contribution we will discuss the current
                      results and give an overview on how magnetic properties of
                      thin films like the depth resolved magnetic moment can be
                      studied with polarized neutron reflectometry.[1] L. Guasco,
                      Yu. N. Khaydukov, S. Pütter, L. Silvi, M. A. Paulin, T.
                      Keller, and B. Keimer, Nat. Comms. 13 (2022) 1486},
      month         = {Jan},
      date          = {2023-01-15},
      organization  = {4th IEEE International Conference on
                       Advances in Magnetics, Moena (Italy),
                       15 Jan 2023 - 18 Jan 2023},
      subtyp        = {After Call},
      cin          = {JCNS-4 / MLZ / JCNS-2 / JCNS-FRM-II},
      cid          = {I:(DE-Juel1)JCNS-4-20201012 / I:(DE-588b)4597118-3 /
                      I:(DE-Juel1)JCNS-2-20110106 /
                      I:(DE-Juel1)JCNS-FRM-II-20110218},
      pnm          = {632 - Materials – Quantum, Complex and Functional
                      Materials (POF4-632) / 6G4 - Jülich Centre for Neutron
                      Research (JCNS) (FZJ) (POF4-6G4)},
      pid          = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G4},
      experiment   = {EXP:(DE-MLZ)MBE-MLZ-20151210 / EXP:(DE-MLZ)MARIA-20140101 /
                      EXP:(DE-MLZ)N-REX-20140101},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/943368},
}