Imaging of confined vortex matter as a probe for anisotropic orderparameter in superconductors

Affiliation: Instituto Balseiro & Low Temperature Lab, Univ. Nac. Cuyo & CNEA, Bariloche, Argentina. Instituto de Nanociencia y Nanotecnología, CONICET-CNEA, Bariloche, Argentina.

Place: conference hall, IMDEA Nanociencia.

Abstract: 

Direct probes for anisotropies in the superconducting order parameter of novel compounds are highly desirable since it helps in a rapid development of possible applications of the material. Vortex imaging with scanning tunnelling microscopy is one direct probe for anisotropic order parameter since in most anisotropic superconductors the spectroscopic halo of vortices is elongated, but this probe is limited to the high magnetic fields range. In the case of low and intermediate fields, direct imaging of the magnetic halo of vortices can be performed by several techniques based in the detection on changes of the local field gradient entailed by a vortex. Nevertheless, in many superconductors with anisotropic order parameters the shape of vortices is not necessarily observed as deformed using these magnetic imaging techniques. Thus, finding another direct probe for anisotropic order parameters applicable in low as well as high fields would be most valuable. Here we present such a probe based in the experimental observation of the alignment of vortex rows and of the deformation of the hexagonal unit cell, both in the crystal direction where the order parameter presents a maximum value, induced by the confinement in samples with typical sizes of few tens of the vortex lattice spacing.

Work done in collaboration with Joaquín Puig, Moira Dolz and Mariela Menghini.

Short bio: 

Prof. Dr. Yanina Fasano has received her PhD in Physics from the Instituto Balseiro at Patagonia, Argentina, in 2003. After a 5-years postdoctoral appointment at the University of Geneva, Switzerland, she joined the Low Temperatures Lab at the Centro Atómico Bariloche of the Atomic National Commission as a permanent researcher of CONICET. In 2021 she became assistant professor at the Instituto Balseiro. Her research is in the field of experimental condensed matter at low temperatures, focusing on superconductivity and vortex matter. She received the Houssay prize of the Ministry of Science, Technology and Innovation of Argentina in 2022, and was honored with the Georg Forster Research Prize from the Alexander von Humboldt Foundation in 2021.