Regensburg 2010 – scientific programme

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KR: Fachverband Kristallographie

KR 10: Poster: Multiferroics (with MA, DF, KR, DS)

KR 10.53: Poster

Tuesday, March 23, 2010, 10:45–13:45, Poster A

Specular and off-specular scattering of neutrons from Si-Fe multilayers — •Anke Teichert, Thomas Krist, Jan E. Hoffmann, Amitesh Paul, and Roland Steitz — Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany

Multilayers (ML) are used as neutron optical devices. These applications require high quality MLs with low interface layer thickness, roughness and high remanence as characterized by a high reflectivity and high polarization efficiency. Here, we want to produce high quality stress-free Si-Fe MLs on Si and glass substrate. All samples (10(10nm Si+10nm Fe)+10nm Si) were produced in a triode sputter machine at p=0.065Pa and Bias voltages from 10 to 65V. Stress and reflectivity measurements were performed at a profilometer and X-ray reflectometer (XRR). Using polarized neutron reflectometry (PNR) and a positive sensitive detector (PSD) at the reflectometer V6 we measured simultaneously specular and off-specular scattering of neutrons. We find a raise in voltage leads to linear decrease of tensile stress with a slope of 5.5MPa/V. At about 60V the samples are nearly stress-free. The grain size decreased with higher Bias voltage. The off-specular data show large diffuse scattering from all samples at low applied magnetic fields (200G, 20G) as well as for samples with high compressive stress at 1030G. It appears as streaks perpendicular to specular reflectivity at Bragg peak positions. They can be interpreted as originating from vertically correlated in-plane magnetic domains. Associated longitudinal fluctuations produce additional diffuse streaks along Bragg peak positions which are independent of the stress within the samples.