Nucleation of Vortex Matter - global and local study using magnetometry, micro-Hall probe and magneto-optical imaging

• Grant number: 08/00090-1
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: November 01, 2008
• End date: October 31, 2009
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Wilson Aires Ortiz
• Grantee: Fabiano Colauto
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 07/08072-0 - Fundamental research in superconductivity and magnetism - systems potentially useful for aplications: advanced oxides and superconductors patterned with artificial structures, AP.TEM

Abstract

Type II superconductors allow penetration of magnetic flux, that could, at first sight, seem harmful to the maintenance of the superconducting state. However, coexistence of superconductivity and magnetism, i.e., the mixed state makes it possible to use superconductors in many applications. There is, however, an inherent problem with this type of superconductors: the vortex motion. Changes on the applied field, transport current, or temperature, are followed by a flux rearrangement in the superconductor, to accommodate the new situation. When flux penetrates in a smooth and homogeneous way, the field profile description can be done through a critical state model. However, in some cases the penetration profile deviates from this scenario and vortices move as avalanches, called flux jumps. We propose a study of vortex dynamics on several superconducting systems through three techniques: bulk magnetometry, magneto-optical imaging, and micro-Hall probe magnetometry. Beyond this study, we also intend to install a magneto-optical setup in the research group with grants requested in a main project - Projeto Temático (2007/08072-0) - to which this Post-doc proposal is associated. So far, there are no magneto-optical imaging setups installed in Brazil. The one currently proposed, will have the additional possibility of superposing AC and DC magnetic field. To our acknowledge, this feature is not found in any other similar facility around the world.