Imaging of vortex matter in Fe-Se superconductors using Bitter decoration technique

M. L. AMIGÓ; R. CORTÉS MALDONADO; G. NIEVA; Y. FASANO

Bariloche

Conferencia; Poster presentado en el XXIII Latin American Symposium on Solid State Physics; 2018

We were able to image single vortex position in superconducting -FeSe and FeSe0;95S0;05 single crystals, bymeans of the Bitter decoration technique. Several structural properties of the vortex array were depicted in thissamples at characteristic magnetic elds applied up to 5 Oe parallel to the c-crystallographic axis of the plateletshaped crystals. In -FeSe crystals, a disordered square symmetry is observed with one of the compact planesoriented along the sample edge at 45 of the a-crystallographic axis. Towards the center of the sample, the latticebecomes more and more disordered and this orientation weakens. In FeSe0;95S0;05, lines with higher vortex densityindicate the presence of twin-boundaries between orthorhombic domains with dierent orientations. The presenceof twin boundaries seems to induce regions of square-like vortex structure.