The Casimir Energy and the Transition Energy of Ferromagnetic Phase in Perovskite Doubles.

Name: Jefferson Rodrigues Rocha
Type: PhD thesis
Publication date: 26/05/2017

Namesort descending Role
Marcos Tadeu DAzeredo Orlando Advisor *

Examining board:

Namesort descending Role
Antonio Brasil Batista Internal Examiner *
Jacyra Ramos Soares External Examiner *
João Francisco Justo Filho External Examiner *
José Alexandre Nogueira Internal Examiner *
Marcos Tadeu DAzeredo Orlando Advisor *

Summary: This thesis is based on Bordag’s theory of Casimir energy. This proposal relates the Casimir energy between conductor plasma planes and the thermal energy in the transition in double ferromagnetic conductive perovskites. Using this association it was possible to calculate
the critical temperature of Curie 𝑇𝑐 relating the fraction of the energy between these materials and the parameters of Sommerfeld 𝛾 of each compound. To evaluate experimentally our proposal we considered the transition temperatures 𝑇𝑐 and the parameters of 3 samples: 𝑆𝑟2𝐶𝑟𝑅𝑒𝑂6,𝑆𝑟2𝐹𝑒𝑅𝑒𝑂6 e 𝐵𝑎2𝐹𝑒𝑅𝑒𝑂6.We have found that for these samples the distance 𝑐 between the conducting planes is associated with the Curie temperature Tc. Our proposal for the calculation of 𝑇𝑐 is consistent with the values found in the literature for samples with these
characteristics (ferrometal and conductive). Based on our theory we proposed the preparation of a new sample that presented a parameter 𝑐 similar to that of the sample 𝑆𝑟2𝐶𝑟𝑅𝑒𝑂6 thus generating a Curie temperature 𝑇𝑐 ≈ 635𝐾,namely:𝑆𝑟1.8𝑌0.2𝐶𝑟𝑅𝑒𝑂6. This new compound is a double perovskite with ferromagnetic metallic characteristics and octahedral geometry formed by planes containing 𝑅𝑒𝑂6 and presenting 𝑇𝑐 = 635𝐾.

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