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E. Jericha, Ch. Gösselsberger, W. Mach, T. Rechberger, Alex Zdarzil, G. Badurek:
"Ultra-small-angle polarized neutron scattering (USANSPOL)";
Poster: Symposium "Research at European Neutron and Synchrotron facilities by Austrian researchers", Wien; 11.11.2013 - 12.11.2013.

Ultra-small-angle scattering of polarised neutrons (USANSPOL) allows for the study of magnetic structure in condensed matter in the micrometre range [1]. This technique takes advantage from the narrow angular width of the Bragg reflection by perfect crystals and is employed in a double-crystal configuration of perfect silicon crystals. Angular-correlated polarisation of the neutron beam is obtained by placing magnetic prisms between the monochromator and the analyser crystal [2]. Then, samples are placed between the polariser prisms and the analyser crystal. The scattering of spin-up and spin-down neutrons is recorded in a single measurement and identified by an angular shift of their respective scattering curves [3].

We have developed a special sample environment and handling system by which anisotropic samples may be aligned in different orientations and be subjected to varying external magnetic fields and mechanical stresses [4,5]. Here, we present experimental results on a variety of magnetic ribbons which represent both novel technologically relevant complex materials which are currently developed for use as magnetic sensors and actuators as well as illustrative examples for methodic development of the USANSPOL technique.

Experiments were carried out under various environmental conditions, including zero-field environment, the influence of external magnetic field, mechanically induced stress, or a combination of both effects, and in magnetically saturated state. Corresponding measurement results allow us to assess the native sample state and thereby also to characterise the manufacturing process which may create form anisotropies. Recording of the scattered neutron intensity under different sample orientations is essential for non-isotropic structures [5]. The evolution of the magnetic structure from this starting point is seen from experiments with applied external magnetic field and/or mechanical stress of varying strength and can be followed up to the angular resolution limit of the technique which corresponds to structure sizes of the order of a few ten micrometres. At the upper end of the internal length scale, we observe the sample under saturation conditions from which we may distinguish crystalline and amorphous states on a microstructure level with considerable implications on the applicability of the materials under investigation.

[1] G. Badurek, E. Jericha, R. Grössinger, R. Sato Turtelli, J. Phys.: Conf. Ser. 211, 2010, 012027.
[2] E. Jericha, G. Badurek, M. Trinker, Physica B 397, 2007, 88.
[3] E. Jericha, G. Badurek, R. Grössinger, Physica B 406, 2011, 2401.
[4] E. Jericha, G. Badurek, Ch. Gösselsberger, D. Süss, J. Phys.: Conf. Ser. 340, 2012, 012007.
[5] E. Jericha, G. Badurek, Ch. Gösselsberger, Physics Procedia 42, 2013, 58.