Fundamental research in superconductivity and magnetism - systems potentially useful for aplications: advanced oxides and superconductors patterned with artificial structures

Abstract

The present thematic project is composed by eight subprojects, devoted to fundamental research on physical systems - magnetic and/or superconducting - exhibiting potentialities for applications. This is the case of certain oxides, called advanced, with unusual magnetic response, such as manganites, certain spinels and the superconducting cuprates. Also included are proposals involving superconducting systems patterned with artificial structures of defects, with which one aims at controlling vortex dynamics, and thus, the critical current, which has important consequences for prospective applications. A study on films and multilayers of TiO2 with Co or Mn is also proposed. Regarding a full comprehension of the physics governing the prominent properties of these systems, a number of open questions still remain, evidencing the importance of additional fundamental research. The Thematic Project will be developed through an existing collaboration among researchers from UFSCar and UNESP-Bauru. More specifically, the collaboration involves Grupo de Supercondutividade e Magnetismo, Physics Department, UFSCar and UNESP's researchers Paulo Noronha Lisboa Filho, Edson Sardella e José Humberto Dias da Silva, from the Physics Department, Faculty of Sciences, who will act as subproject coordinators. There are also some important external collaborations, with Brazilian and foreign groups. Besides, an already existent, significant research infrastructure will be available for development of the project, involving facilities for production and characterization - structural and microstructural - of specimens, which will be studied through a variety of techniques, such as magnetization, AC-susceptibility and harmonic analysis, local magnetic field sensing, magneto-transport, specific heat, thermal transport, magneto-optical imaging. For the sake of clarity, the eight subprojects composing this Thematic Project were grouped according to similarities among the problems they embrace: Group 1 treats the magnetic response of superconducting systems with structures of defects, its projects being: (i) Interaction of Vortex Matter with large, non-correlated defects; (ii) Interaction of Vortex Matter with columnar defects; (iii) Structured mesoscopic systems; (iv) Thermomagnetic instabilities and flux avalanches in MgB2 and Nb; (v) Studies of the Vortex Lattice in Nanostructured Superconductors. Group 2, focused on the development of magnetic and superconducting materials in nanoscopic scale, includes the following topics: (vi) Magnetic response of samples of nanoscopic scale with structural inhomogeneities; (vii) Study of the magnetic phase diagram and substitucional effects in magnetic systems with perovskite and spinel structures. Group 3 consists of a single subproject, in which we propose studies leading to optimize preparation conditions, using the RF magnetron sputtering technique, of films and multilayers of TiO2:MT, where MT is a transition metal: (viii) Preparation of films and multilayers of TiO2:MT (MT = Co or Mn). (AU)