Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 64: Superconductivity: Heterostructures, Andreev Scattering, Vortex Physics
TT 64.9: Talk
Thursday, March 14, 2013, 17:15–17:30, H21
Neutron dark field imaging of domain structures in superconductors — •Tommy Reimann1,2, Christian Grünzweig3, Sebastian Mühlbauer1, Michael Schulz1,2, and Peter Böni2 — 1TU München, Forschungsneutronenquelle Heinz Maier Leibnitz (FRM II), 85747 Garching, Germany — 2Physik Department E21, TU München, 85747 Garching, Germany — 3Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland
In the intermediate mixed state (IMS) of a type II superconductor (SC), the sample splits up into field-free Meissner domains and Shubnikov domains which carry the vortex lattice. The IMS is analog to the intermediate state (IS) of a type-I superconductor with normal and superconducting domains. Experiments on the topology of both states show a variety of different patterns including striped, dendritic and bubble phases, which represent typical domain morphologies also seen in various other physical contexts. A detailed investigation of domain patterns offers the possibility to study general characteristics of domain nucleation and morphology as well as the physical properties of vortex-vortex interactions. Domain structures in SC are typically investigated by surface sensitive techniques such as magneto optical imaging, but flux pinning as well as Landau branching can significantly hamper the deduction of bulk properties. In this talk we show how neutron grating interferometry (nGI) can be used as a tool for the unambiguous identification of bulk properties. The capability of this unique technique will be demonstrated on Pb and Nb single crystals, which are classical representatives of type I and type II SC respectively.