Synthesis and characterization of the Iron Based Superconductors LnFeAsO1xFx (ln = la, CE)

• Grant number: 19/23879-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2019
• End date: July 31, 2021
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Ricardo Donizeth dos Reis
• Grantee: Wagner Ribeiro da Silva Neto
• Host Institution: Centro Nacional de Pesquisa em Energia e Materiais (CNPEM). Ministério da Ciência, Tecnologia e Inovação (Brasil). Campinas , SP, Brazil
• Associated research grant: 18/00823-0 - New topological states of matter under extreme conditions, AP.JP

Abstract

Although BCS theory provided a good description of superconducting materials back in 1957, it is now known that several new materials can lead to superconductivity through more complex mechanisms. Iron-Based Superconductors (IBS) have been receiving great attention currently since they present superconductivity in higher temperatures as to previous synthesized ones. In these materials, only small changes of an appropriate external control parameter can change the properties of a material fundamentally, with the physical properties depending on a delicate interplay of different physical effects. Be able to tune this interplay is essential for the understanding of the superconductivity in these compounds. Taking into consideration the common characteristics among IBS compounds, already illustrated in literature, this project proposes synthesis and characterization of the 1111 materials, whose molecular formula isLnFeAsO1ýxFx, with Ln as La, Sm, Nd or Ce elements, as polycrystals and single crystals, in two different steps: first, syntheses will take place at Campinas with the Prof. Pagliuso group, focusing on the materials where Ln could be La and Ce metals; secondly, the applicant will make use of an exchange partnership of our group and the Max Planck group, to travel to Dresden where he will be able to synthesize the IBS materials applying Sm and Nd, in addition to focusing in giving rise of other possible procedures for crystal growth. In addition, in the second year of this project, the student will participate in the XRD and XAS (XANES and XMCD) measurements as a function of pressure (hydrostatic and uniaxial), which will happen at the EMA beamline of the new Brazilian Synchrotron, Sirius. In this part of the project, we will study the correlations between structure and magnetism as a function of pressure, which will be fundamental for us to investigate the role of Fe ion in the superconducting state of these compounds. Lastly, the applicant will pursue a formation in basic education on the field of Condensed Matter Physics as a starting trajectory for his master's degree.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

DE FIGUEIREDO, A. G.; CANTARINO, M. R.; NETO, W. R. DA SILVA; PAKUSZEWSKI, K. R.; GROSSI, R.; CHRISTOVAM, D. S.; SOUZA, J. C.; PIVA, M. M.; FREITAS, G. S.; PAGLIUSO, P. G.; et al. Orbital localization and the role of the Fe and As 4p orbitals in BaFe2As2 probed by XANES. Physical Review B, v. 105, n. 4, JAN 21 2022. (17/10581-1, 18/11364-7, 19/05150-7, 15/15665-3, 20/12283-0, 20/13701-0, 19/23879-4, 19/04196-3)