Journal of large-scale research facilities, 2, A92 (2016) http://dx.doi.org/10.17815/jlsrf-2-90 Published: 17.11.2016 POLARIMETER: A Soft X-Ray 8-Axis UHV- Di�ractometer at BESSY II Helmholtz-Zentrum Berlin für Materialien und Energie * Instrument Scientists: - Dr. Andrey Sokolov, Helmholtz-Zentrum Berlin für Materialien und Energie, phone: +49 30 8062-12986, email: andrey.sokolov@helmholtz-berlin.de - Dr. Franz Schäfers, Helmholtz-Zentrum Berlin für Materialien und Energie, phone: +49 30 8062-12946, email: franz.schaefers@helmholtz-berlin.de Abstract: A versatile UHV-polarimeter for the EUV XUV spectral range is described which incorpo- rates two optical elements: a phase retarder and a re�ection analyzer. Both optics are azimuthally rotatable around the incident synchrotron radiation beam and the incidence angle is freely selectable. This allows for a variety of re�ectometry, polarimetry and ellipsometry applications on magnetic or non-magnetic samples and multilayer optical elements. 1 Introduction The high precision 8-axis ultra-high vacuum compatible (UHV)-polarimeter (Schäfers et al., 1999) is a multipurpose instrument which can be used as a multilayer-based self-calibrating polarization detector for linearly and circularly polarized UV- and soft X-ray light (Gaupp et al., 2013; MacDonald et al., 2009). It can also be used for the characterization of either re�ection or transmission properties (re�ectometry) (Eriksson et al., 2006; Schäfers, 2000) as well as to determine polarizing and phase retarding properties (ellipsometry) of any optical element (Uschakow et al., 2013). Magneto-optical experiments are possible in transmission, as the XMCD or XMLD (Magnetic Circular / Linear Dichroism) that are intensity measurements (Mertins et al., 2002). Additionally a polarization analysis of the transmitted or re�ected light is possible which allows for Faraday-, Voigt- or Kerr-e�ect technique (L-MOKE, T-MOKE) to investigate thin �lms as well as mag- netic multilayers (Mertins et al., 2001; Zaharko et al., 2002). Independent two-dimensional rotation of the detector enables any non-specular magnetic scattering experiment on magnetic dots or grains. A load-lock transfer chamber allows for quick and easy sample exchange. *Cite article as: Helmholtz-Zentrum Berlin für Materialien und Energie. (2016). POLARIMETER: A Soft X-Ray 8-Axis UHV-Di�ractometer at BESSY II. Journal of large-scale research facilities, 2, A92. http://dx.doi.org/10.17815/jlsrf-2-90 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-2-90 http://dx.doi.org/10.17815/jlsrf-2-90 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 2, A92 (2016) http://dx.doi.org/10.17815/jlsrf-2-90 Figure 1: Schematic view of the POLARIMETER station. 2 Instrument application Typical applications are: • Characterization of optical elements • Re�ection, transmission properties (s-, p-pol.) • Polarizing properties (phase retardation) • Determination of polarization of incident light (Stokes S0,1,2,3) • Resonant Magnetic Scattering (specular and di�use) • Intensity spectroscopy: MCD, LMD, Kerr-e�ect (L, T-MOKE) • Polarization spectroscopy: Faraday-, Voigt, Kerr-e�ect Methods: • Elipsometry • Polarimetry • Re�ectometry 2 http://dx.doi.org/10.17815/jlsrf-2-90 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-2-90 Journal of large-scale research facilities, 2, A92 (2016) 3 Technical Data Experiment in vacuum 10−9 mbar Temperature range 280 - 480 K Max. sample size 50 x 50 x 11 mm3 Min. sample size 10 x 10 x 0.5 mm3 Incidence angle scan range 0°≤ΘP, ΘA ≤ 90° Azimuthal angle scan range 0°≤α , β ≤370° Detector scan range (in plane) 0°≤Θ2A≤180° (o�-plane) -10°≤ΘD≤27° Min. step size for all motors 0.001° Sample – Detector Distance 150 mm Magnetic �elds (in-/o�-plane) -450 < H < 450 Oe (long./transv.) Detector GaAsP-photodiode with Keithley elec- trometer 617 (6514) Detector size 4 x 4 mm2, 0.2 x 4 mm2 Load-lock, Magazine In-situ storage of up to 10 samples Higher order �lters Be, B, C6H8, Ti, Cr, Fe Collimator pinholes ∅ 0.2 – 2.0 mm Table 1: Technical data of the POLARIMETER station. References Eriksson, F., Ghafoor, N., Schäfers, F., Gullikson, E. M., & Birch, J. (2006). Interface engi- neering of short-period Ni/V multilayer X-ray mirrors. Thin Solid Films, 500(1-2), 84 - 95. http://dx.doi.org/10.1016/j.tsf.2005.11.019 Gaupp, A., Schäfers, F., MacDonald, M., Uschakow, S., Salashchenko, N. N., & Gaykovich, P. K. (2013). Carbon K-edge polarimetry with Cr/Sc multilayers. Journal of Physics: Conference Series, 425(12), 122013. http://dx.doi.org/10.1088/1742-6596/425/12/122013 MacDonald, M. A., Schäfers, F., & Gaupp, A. (2009). A single W/B4C transmission multi- layer for polarization analysis of soft x-rays up to 1keV. Opt. Express, 17(25), 23290–23298. http://dx.doi.org/10.1364/OE.17.023290 Mertins, H.-C., Abramsohn, D., Gaupp, A., Schäfers, F., Gudat, W., Zaharko, O., . . . Oppeneer, P. M. (2002). Resonant magnetic re�ection coe�cients at the Fe 2 p edge obtained with linearly and circu- larly polarized soft x rays. Phys. Rev. B, 66, 184404. http://dx.doi.org/10.1103/PhysRevB.66.184404 Mertins, H.-C., Oppeneer, P. M., Kuneš, J., Gaupp, A., Abramsohn, D., & Schäfers, F. (2001). Observation of the X-Ray Magneto-Optical Voigt E�ect. Phys. Rev. Lett., 87, 047401. http://dx.doi.org/10.1103/PhysRevLett.87.047401 Schäfers, F., Mertins, H.-C., Gaupp, A., Gudat, W., Mertin, M., Packe, I., . . . Eriksson, M. (1999). Soft- x-ray polarimeter with multilayer optics: complete analysis of the polarization state of light. Appl. Opt., 38(19), 4074–4088. http://dx.doi.org/10.1364/AO.38.004074 Schäfers, F. (2000). Multilayers for the EUV/soft X-ray range. 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Exchange coupling in fe/nio/co �lm studied by soft x-ray resonant magnetic re�ectivity. Phys. Rev. B, 66, 134406. http://dx.doi.org/10.1103/PhysRevB.66.134406 4 http://dx.doi.org/10.17815/jlsrf-2-90 http://dx.doi.org/10.1088/1742-6596/425/15/152011 http://dx.doi.org/10.1088/1742-6596/425/15/152011 http://dx.doi.org/10.1103/PhysRevB.66.134406 https://creativecommons.org/licenses/by/4.0/ Introduction Instrument application Technical Data