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Lichtenbergstr.1
85748 Garching

MARIA

Magnetic reflectometer with high incident angle

MARIA scheme MARIA scheme

The neutron reflectometer MARIA with polarization analysis has been designed for the investigation of thin magnetic layered structures down to the monolayer scale and lateral structures. The reflection of polarised neutrons allows to determine individually the density and the modulus and the direction of the magnetisation vector of buried layers.

MARIA is optimised for layer thicknesses between 3 – 300 Å and lateral structure sizes from nm to µm sizes. Consequently the instrument is designed for small focused beam and sample sizes of 1 cm2 at λ = 4.5 Å (available: 4.5 Å < λ < 40 Å) in a vertical orientation with a maximum incident angle of 180° and outgoing angle ranging from -14° to 100°. Maria provides polarisation analysis in standard operation, where the beam is polarised by a polarising guide (z-geometry; 4.5 Å < λ < 10 Å) and analysed by a wide angle 3He-cell.
Beside the above described reflectometer mode with good resolution in the horizontal scattering plane, MARIA can be used in the GISANS mode with additional resolution in the vertical direction. The latter mode allows one to measure lateral structures down to the nm scale.

All parts of MARIA are controlled by a computer system according to the “Jülich-Munich” standard based on a Linux workstation. This allows a flexible remote control with automatic scan programs, including the control of sample environment as cryostat and electromagnet.

The optimal sample size for MARIA is 10 × 10 mm2 with the following parameters:

  • Thin magnetic layers down to sub mono layers
  • Polarization analysis as standard
  • Layer thickness of 1 – 300 Å optimized, but – 1000 Å (multi layers) should be feasible
  • Lateral structures of nm to µm

Besides the described cryogenic temperatures and magnetic fields MARIA provides a fully equipped Oxide- MBE (Molecular Beam Epitaxy) system to the user. That means users may fabricated their own samples on-site and measure them with MARIA!

Typical Applications

With scattering under grazing incidence we investigate depth-resolved the laterally-averaged magnetizations and the correlations between their lateral fluctuations. With an additionally polarized neutron beam we derive a vector information on the laterally-averaged magnetization (reflectivity) and on the correlations between their lateral fluctuations (off-specular scattering – µm length scale, GISANS – nm length scale).

In general MARIA can be used for measurements of magnetic roughness, the formation of magnetic domains in thin layered structures, lateral structures, etc. (polarized mode) and density profiles, structures of solid polymer layers, etc. (unpolarized mode with higher intensity).
Furthermore possible without the need for multilayers investigation of:

  • Diluted semi conducters
  • Influence of the substrate
  • Interfaces between oxide materials
Sample Environment

At the sample position a Hexapod with an additional turntable (360°) is installed, which can take a load up to 500 kg. In the standard configuration magnetic fields are provided up to 1.3 T (Bruker electromagnet) and cryogenic temperatures down to 4 K (He closed cycle Cryostat). Beside this standard setup the complete sample environment of the JCNS can be adopted to MARIA so that magnetic fields up to 5 T and temperatures from 50 mK to 500 K are available.

Technical Data

Primary beam

  • Neutron guide NL5-N: vertically focussing elliptic guide
  • Monochromator: Velocity selector
  • Wavelength:
    • 4.5 Å – 10 Å (polarized)
    • 4.5 Å – 40 Å (unpolarized)
  • Resolution:
    • 10 % velocity selector
    • 1 %, 3 % Fermi chopper
  • Double reflection polarizer
  • Horizontal scattering plane

Flux at sample

  • Expected pol. flux 5 · 107 n cm-2 s-1 for 3mrad collimation

Distances and angles

  • 4100 mm distance S1 – S2 (collimation)
  • 400 mm distance S2 – sample
  • 50 mm × 40 mm (w × h) max. opening S2
  • 1910 mm distance sample – detector
  • 120° maximum detector angle
  • GISANS option: 4 m collimation length

Accessible Q-range

  • Reflectometry:
    • Qz- range 0.002 Å-1 – 3.2 Å-1
    • Qx- range 6 · 10-5 – 0.001 Å-1
    • αf -14° – 100°
  • GISANS option: Qy- range 0.002 Å-1 – 0.2 Å-1

Polarization analysis

  • ³He cell

Detector

  • 2D PSD detector:
    • size 400 × 400 mm2
    • resolution 2 × 3 mm (h × v)

Instrument Scientists

Dr. Stefan Mattauch
Phone: +49.(0)89.289.10709
E-Mail:

Dr. Alexandros Koutsioumpas
Phone: +49.(0)89.289.10674
E-Mail:

Dr. Sabine Pütter
Phone: +49.(0)89.289.10742
E-Mail:

MARIA
Phone: +49.(0)89.289.10795

Operated by

JCNS

Gallery

MARIA
MARIA

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