Estudo de Espalhamento Raman no Iridato Sr2IrO4 com substituções isovalentes de Ca e Ba no sitio do Sr

Author(s)

Adimir Italo Vilca Morales

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin
• Defense date: 2024-06-26

Examining board members

Eduardo Granado Monteiro da Silva; Túlio Costa Rizuti da Rocha; Ulisses Ferreira Kaneko

• Advisor: Eduardo Granado Monteiro da Silva

Abstract

Novel phenomena arising from the interplay of strong spin-orbit coupling and moderate electron correlations have attracted attention of the scientific community to the exotic physics presented by Sr2IrO4 and its family of iridates. The multiorbital character of the pseudospin Jef f = 1/2 state and the degrees of freedom of the crystal structure play a crucial role for the stabilization of its magnetic behavior. Thus, understanding the details of Sr2IrO4 via tunable parameters is important for a realistic description of this system. To achieve this goal, we measured with Raman spectroscopy the low-energy excitations of the system Sr2IrO4 under chemical pressure, obtained by isovalent substitutions at the Sr2+ site. Our results indicate crystal environment changes due to the chemical substitutions' impact on the spin-orbit coupled Jef f = 1/2 state, leading to an enhanced pseudospin-phonon coupling and interference between phonons and an electronic continuum. The effect of the chemical substitution onto the lattice parameters, the magnetic properties and the single magnon excitation show the important role played by the local structural distortions on the stabilization of the collective spin-orbital state Jef f = 1/2 and its longrange magnetic order (AU)

• FAPESP's process: 18/18653-4 - Search for emergent electronic states in the two-dimensional Iridates (Sr1-xAx)2IrO4 (A=Ca, BA)
• Grantee: Adimir Italo Vilca Morales
• Support Opportunities: Scholarships in Brazil - Master