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@INPROCEEDINGS{Ptter:861071,
      author       = {Pütter, Sabine and Syed Mohd, Amir and Mattauch, Stefan
                      and Koutsioumpas, Alexandros and Brückel, Thomas},
      title        = {{A} transfer chamber for polarized neutron reflectometry on
                      thin films under {UHV} conditions},
      reportid     = {FZJ-2019-01645},
      year         = {2019},
      abstract     = {A transfer chamber for polarized neutron reflectometry on
                      thin films under UHV conditionsS. Pütter*,1, A. Syed Mohd1,
                      S. Mattauch1, A. Koutsioubas1, and T. Brückel21. Jülich
                      Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz
                      Zentrum (MLZ) Forschungszentrum Jülich GmbH, Garching,
                      Germany2. Jülich Centre for Neutron Science and Peter
                      Grünberg Institut, JCNS-2/PGI-4: Quantum Materials and
                      Collective Phenomena, Forschungszentrum Jülich GmbH,
                      Jülich, Germany*s.puetter@fz-juelich.deWithin JRA 5 of the
                      NFFA project we have designed and fabricated a versatile
                      small ultra high vacuum (UHV) chamber which can be used for
                      sample transfer and measurement at the polarized neutron
                      reflectometer MARIA of the Jülich Centre for Neutron
                      Science (JCNS) at the Heinz Maier-Leibnitz Zentrum in
                      Garching, Germany and elsewhere. [1]We were motivated by the
                      problem that the investigation of ultrathin films which are
                      sensitive to ambient air is a challenge at large scale
                      instruments as the capabilities for on-site growth UHV
                      chambers to measure in-situ are limited, mostly due to
                      lacking space. A common workaround is the use of protecting
                      cap layers on top of the thin film. However, cap layers may
                      change the physical properties of the sample [2].The samples
                      are prepared in the JCNS thin film laboratory by molecular
                      beam epitaxy and moved into the compact chamber for transfer
                      to the nearby reflectometer MARIA. The transfer chamber is
                      based on a DN 40 cube equipped with sapphire windows, an
                      SAES getter pump and a wobble stick, which serves also as a
                      sample holder for samples of up to 1 cm2. The pressure in
                      the transfer chamber is kept in the 10−10 mbar range
                      during transport and measurement. The chamber fits perfectly
                      into the magnet of the reflectometer. Polarized neutron
                      reflectivity (PNR) measurements can be performed at room
                      temperature and in magnetic fields in the sample plane of up
                      to 300 mT.Fig. 1: Photo of the transfer chamber (W.
                      Schürmann) For testing the chamber Co thin films were
                      deposited on Pt buffered MgO(001) substrates with the MBE
                      system and transfered to MARIA. PNR measurements of these
                      films were performed first under UHV condition and then
                      after exposing to ambient air. The fitting of the PNR data
                      shows that the surface of the Co film oxidizes in air but
                      remains free from contamination in the UHV transport
                      chamber.Second we varied the Co film thickness to study the
                      magnetic moment by PNR. The results reveal the vertical
                      depth profile of the magnetic moment of the Co films. The
                      magnetisation is not constant but smeared out at the edges,
                      due to roughness and intermixing. We find an evolution of
                      the magnetic moment of Co which may be separated in a bulk
                      and a surface contribution.The transfer chamber is offered
                      within the NFFA project to users who want to perform PNR
                      measurements and sample preparation with the MBE system.
                      This project has received funding from the EU’s H2020
                      research and innovation programme under grant agreement n.
                      654360.References:[1] A. Syed Mohd, S. Pütter, S. Mattauch,
                      A. Koutsioubas, H. Schneider, A. Weber, and T. Brückel,
                      “A versatile UHV transport and measurement chamber for
                      neutron reflectometry under UHV conditions”, Rev. Sci.
                      Instrum., vol. 87, pp. 123909, 2016[2] F. El Gabaly, K. F.
                      McCarty, A. K. Schmid, J. de la Figuera, M. C. Muñoz, L.
                      Szunyogh, P. Weinberger, and S. Gallego,”Noble metal
                      capping effects on the spin-reorientation transitions of
                      Co/Ru(0001)”, New J. Phys., vol. 10, pp. 073024, 2008},
      month         = {Feb},
      date          = {2019-02-20},
      organization  = {Second NFFA Europe Science Workshop,
                       Milan (Italy), 20 Feb 2019 - 21 Feb
                       2019},
      subtyp        = {After Call},
      cin          = {JCNS-FRM-II / JCNS-2},
      cid          = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
                      I:(DE-Juel1)JCNS-2-20110106},
      pnm          = {6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623)
                      / 6G15 - FRM II / MLZ (POF3-6G15) / 524 - Controlling
                      Collective States (POF3-524) / 6212 - Quantum Condensed
                      Matter: Magnetism, Superconductivity (POF3-621)},
      pid          = {G:(DE-HGF)POF3-6G4 / G:(DE-HGF)POF3-6G15 /
                      G:(DE-HGF)POF3-524 / G:(DE-HGF)POF3-6212},
      experiment   = {EXP:(DE-MLZ)MARIA-20140101 / EXP:(DE-MLZ)MBE-MLZ-20151210},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/861071},
}