Superconductivity and the superconducting phase transition: Two - phase ceramic mixtures (Hg, Re - 1223)

Name: Fernando Henrique Santos Eleutério
Type: PhD thesis
Publication date: 15/12/2017
Advisor:

Namesort descending Role
Humberto Belich Junior Advisor *

Examining board:

Namesort descending Role
Carlos Augusto Cardoso Passos External Examiner *
Humberto Belich Junior Advisor *
José Abdalla Helayel Neto External Examiner *
José Luis Passamai Junior External Examiner *
Sebastião Alves Dias External Examiner *

Summary: The focus of this work is the investigation of the two intrinsic phases of structural superconductors, using as object of study the magnetic response and its granular composition. By investigating the magnetic susceptibility to ac in the polycrystalline pottery of the mercury base doped with rhenium (Hg0.82 Re0.18 Ba2 Ca2 Cu3 O8.16 - (Hg, Re) -1223) with the precursor with optimum oxygen content, pulverized
(reduced to powder and sieved) it was possible to determine the critical temperature of the sample and to observe that it depends on the size of each of the grain. For the 20 μm particle only a critical temperature of 133K was found, but it has two critical temperatures (133K and 98K) as the particle size is further reduced to a mesoscopic scale of 600nm. This fact was elucidated by an extension of the Ginzburg-Landau theory using two order parameters to parameterize the complex scalar field and making the connection with the microscopic model responsible for describing the peculiarities of these types of grains.

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