Panoramics of vortex matter in FeSe and FeSeS at low fields

CORTÉS MALDONADO, RAÚL; FASANO, YANINA; AMIGÓ, M. LOURDES; ARAGÓN SÁNCHEZ, JAZMÍN; NIEVA, GLADYS

Conferencia; 18th International Conference on Vortices in Superconductors; 2021

We apply magnetic decoration to obtain large field-of-view images of the vortex matter nucleated at the surface of FeSe and FeSeS single crystals at low fields (5-15 Oe). We analyse the structural properties in thousands-vortices fields-of-view and found that the non hyperuniform structure is composed by a mixture of isotropic and distorted hexagonal domains. Structure factor and Delaunay triangulation analysis indicate that the latter domains correspond to an oblique structure obtained by expanding or compressing the hexagon along the Fe-Fe bond crystallographic direction (a or b axis). Nevertheless, at the edge of the sample few vortex rows are aligned at 45° from the a and b axis, mimicking the sample geometry.