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Studies of inhomogeneity effects on properties of superconducting materials

Author(s):
Luis Augusto Gomes Baring
Total Authors: 1
Document type: Master's Dissertation
Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin
Defense date:
Examining board members:
Renato de Figueiredo Jardim; Pascoal Jose Giglio Pagliuso
Advisor: Iakov Veniaminovitch Kopelevitch
Abstract

In this work we study the physical properties of bismuth samples. Crystalline bulk bismuth, in the rhombohedral phase, is not superconducting, but, in the cubic phase, for example (obtained under pressure), in films and in the amorphous phase, may present superconducting transition. We observed superconductivity in a bismuth virgin powder and in samples prepared upon annealing this powder. Due to the small volumetric superconducting fraction we suspect that the superconductivity is related to the sample's surface. Moreover, the superconducting properties are strongly dependent upon the annealing conditions (these samples may be either superconducting or not). We also performed magnetotransport measurements in a single-crystalline bismuth sample and observed a characteristic feature of this material, namely, metal-insulator transition driven by applied magnetic field (AU)