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Studies of electronic and magnetic correlation in iron based superconductors and molecular conductors via Nuclear Magnetic Ressonance (NMR) and Quadrupolar (NQR)

Grant number: 16/14436-3
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): October 01, 2016
Effective date (End): June 15, 2020
Field of knowledge:Physical Sciences and Mathematics - Physics - Condensed Matter Physics
Principal Investigator:Ricardo Rodrigues Urbano
Grantee:Paulo Eduardo Menegasso Filho
Home Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
Associated research grant:12/05903-6 - Nuclear magnetic resonance of novel complex and advanced materials in condensed matter physics, AP.JP


Systems with correlated behavior of electrons such as Magnetism and Superconductivity are of great relevance within Condensed Matter Physics. Among the physical systems of interest in this project, special attention will be given to the iron based superconductors, discovered in the last decade, and to the organic conductors.Besides his high critical temperature e the unconventional pairing mechanism, the iron-arsenide systems presents intriguing physical properties also at the normal state (PM) and also in the magnetically ordered state (Spin Density Wave). Equivalent importance is given to the molecular conductors, whose has been used in the exploration of Mott Physics with similar properties with the superconducting oxides of high Tc, presenting strong electronic correlation such as the charge ordering phase observed.Within this thematic basically we will give emphasis to the exploration of several phenomena emerging in such systems. Members of 122 family of the iron based superconductors such as BaFe2As2 are quite convenient for possibility chemical substitution in the distinct sites of Ba for Eu, Fe for Co, Cu, Ni and Mn and also As for P. One specific objective will be to understand the magnetic field influence over the magnetic and structural transition that happens in this materials due to doping/substitution. Such study will reveal the relation between the lattice and the spin degrees of freedom, which can lead to a better comprehension concerning the unconventional high critical temperature superconductivity in such systems.In the frame of organic conductors, we intend to explore particularly the Fabre salts of family (TMTTF)2X (with X = PF6, ReO¬4, among others). Special emphasis will be given to the exploration of magnetoelectric properties of such family, in which a charge ordering attenuation is expected with magnetic field application. The system (TMTTF)2PF6, for instance, is the most susceptible to such attenuation and will be used in the study of ionic substitution which is still open. Notwithstanding, we plan also to explore the magnetoelectric effects in the non-centrosymmetric system (TMTTF)2ReO4 which presents ionic ordering, possible lack of charge ordering effects and possible anomalies under strong magnetic field effects. Such results, once confirmed by our study, will have great impact in the literature and community.Such investigation will start with thermodynamical and electrical transport characterization macroscopic experiments (magnetization, specific heat, dielectric constant, etc.). The obtained results will give strong support to the systematic microscopic Nuclear Magnetic Resonance (NMR and NQR) experiments via measurements of specific magnetic displacement to each site, knight shift, as well as spin dynamics via measurements of spin-spin (1/T2) and spin-lattice (1/T1) relaxation as function of several external parameters such as temperature, magnetic field, anysotropy (angular variation) and chemical/hydrostatic pressures.

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 QUEIROZ, THIAGO B.; CABRERA-BAEZ, MICHAEL; MENEGASSO, PAULO; MARTINEZ, EDUARDO D.; GARCIA FLORES, ALI F.; RETTORI, CARLOS; URBANO, RICARDO R. Probing Surface Effects on alpha-NaYF4 Nanoparticles by Nuclear Magnetic Resonance. Journal of Physical Chemistry C, v. 124, n. 17, p. 9523-9535, APR 30 2020. Web of Science Citations: 0.

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