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Domain Formation in the Type-II/1 Superconductor Niobium: Interplay of Pinning, Geometry, and Attractive Vortex-Vortex Interaction



Tommy Reimann, Michael Schulz, David F. Mildner, Markus Bleuel, Annie Brulet, Ralph P. Harti, Georg Benka, Andreas Bauer, Peter Boni, Sebastian Muhlbauer


Vortex attraction which can cause a bundling of vortices has been observed in a multitude of type-II superconductors, While its underlying mechanisms have been extensively studied, the morphology of the emerging vortex superstructure has only been weakly considered. Here, we present a comprehensive experimental study on the type-II/1 superconductor niobium which focuses on the transformation of its homogeneous vortex lattice into an inhomogeneous domain structure at the onset of vortex attraction. By means of small-angle neutron scattering, ultra-small-angle neutron scattering and neutron grating interferometry, the vortex lattices, its micrometer-scale vortex domain structure as well as its distribution could be investigated while crossing the transition to the intermediate mixed state which is characterized by vortex attraction. We found that the phase separation of the vortex lattice into an irregular domain structure takes place via a process showing strong similarity to spinodal decomposition. While pinning disorders the domain morphology, the characteristic length scale of the domain structure is govern by an interplay of field distortion energy and domain surface tension. Finally, geometric barriers in the disc-shaped samples provoke an inhomogeneous distribution of domains on the macroscopic scale.
Physical Review B


Reimann, T. , Schulz, M. , Mildner, D. , Bleuel, M. , Brulet, A. , Harti, R. , Benka, G. , Bauer, A. , Boni, P. and Muhlbauer, S. (2017), Domain Formation in the Type-II/1 Superconductor Niobium: Interplay of Pinning, Geometry, and Attractive Vortex-Vortex Interaction, Physical Review B, [online], (Accessed July 23, 2024)


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Created October 9, 2017, Updated October 12, 2021