Unveiling the magnetic and optical properties of barium bismuthate thin films with distinct Ba/Bi ratios

Autor(es)

Acero, G. ; Ponce, M. A. ; Moura, F. ; Simoes, A. Z.

• Tipo de documento: Artigo Científico
• Fonte: Materials Chemistry and Physics; v. 322, p. 13-pg., 2024-06-01.

Resumo

This research aims to investigate the optical and magnetic properties of BaBiO 3 (80:20), BaBiO 3 (50:50), and BaBiO 3 (30:70) thin films obtained by the polymeric precursor method. For better sample designations, the following codes were employed: (80:20) (BBO82), (50:50) (BBO55), and (30:70) (BBO37). The observed properties for barium bismuthates thin films were elucidated in terms of bismuth and oxygen vacancies as well as grain morphology, which can be controlled by stoichiometric changes (Ba/Bi ratios). According to the x-ray results the films crystallize in a rhombohedral BaBiO 3 structure with an R -3R space group without any secondary phase as confirmed by Rietveld analyses. According to the photoluminescence results, x-ray photoelectron spectroscopy measurements as well as the law of approach to saturation (LAS), there are a significant presence of oxygen vacancies and vacancy clusters [ BiO 5 .V . ] in the films with high proportion of bismuth. The optical and o magnetic properties developed by these films are originated from the following factors: tilting of BiO 6 clusters which changes the length and angle of Bi - O - Bi bonds, creating a magnetic field responsible for the distinct M r / M s ratios, the formation of bipolarons caused by charge transfer between [BiO 6 ] and [BiO 5 . V o & sdot; ] due to the oxygen vacancies formation, plate-like morphology which makes the domains easier to be switched under an applied external field resulting in a superparamagnetic behavior, charge disproportionation of various valence states (Bi +3 and Bi +5 ). Based on these results, new potential devices can emerge as possible tools to be applied in switches, actuators, spintronics, magnetic field sensors, etc. (AU)

• Processo FAPESP: 13/07296-2 - CDMF - Centro de Desenvolvimento de Materiais Funcionais
• Beneficiário: Elson Longo da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs