Banca de QUALIFICAÇÃO: SAMUEL JÔNATAS DE CASTRO LOPES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : SAMUEL JÔNATAS DE CASTRO LOPES
DATE: 30/06/2022
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

SEGMENTED NANOWIRES (Ni/Cu): EFFECT OF MODULATION ON THE LINE WIDTH OBTAINED BY FERROMAGNETIC RESONANCE

KEY WORDS:

magnetic nanowires; electrodeposition; carbon; line width, ferromagnetic resonance.

PAGES: 85
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

In the present work, continuous and composition-modulated magnetic nanowires were electrodeposited within commercial porous alumina membranes with a diameter of approximately 250 nm. Continuous and composition-modulated magnetic wires were grown using conventional working electrode (gold). An optimization of the synthesis process was obtained with the use of conductive carbon ink, commonly used in electron microscopy, as a working electrode, contributing to the novelty of this research. Morphological, structural and magnetic characterizations were performed to confirm the formation of continuous and composition-modulated magnetic wires. The microscopy performed for the samples that used gold as a working electrode, showed good surface quality and proved the modulation by composition. The structural characterization revealed the presence of nickel for continuous wires and nickel and copper for wires modulated by composition. The magnetic study confirmed the ferromagnetic character of the samples, and a broadening of the linewidth was observed when the ferromagnetic segments were separated by non-magnetic layers. The sample that used carbon as a working electrode confirmed the optimization of the synthesis process, since the electron microscopy images revealed the formation of wires modulated by composition with excellent surface quality. The structural study confirmed the presence of nickel and copper with a face-centered cubic structure, corroborating the results obtained for the samples that used gold as a working electrode. An elemental mapping was performed and proved the nanometric control of the modulation, with low copper contamination in the ferromagnetic segments. This thesis contributes to the obtainment of continuous and compositionmodulated magnetic wires via electrodeposition, which allow the study of the influence of the nonmagnetic layer on the line width obtained by ferromagnetic resonance.

BANKING MEMBERS:
Externa à Instituição - GILVANIA LUCIA DA SILVA VILELA - UPE
Externo ao Programa - 3091529 - MICHAEL CABRERA BAEZ
Externo à Instituição - YUSET GUERRA DAVILA - UFPI