Banca de QUALIFICAÇÃO: DIEGO BERNABE ORTIZ SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : DIEGO BERNABE ORTIZ SILVA
DATE: 27/09/2021
LOCAL: google meet
TITLE:

MICROMAGNETIC SIMULATION IN DISK AND ELLIPSOID ARRANGEMENTS MANUFACTURED BY OPTICAL LITHOGRAPHY.

KEY WORDS:

Microlithography. DWL. Magnetic arrangements. Permalloy. OOMMF

PAGES: 82
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

The properties of object arrays have gained a lot of attention from the scientific
community due to applications and still unsolved academic problems. An array can be studied
magnetically using microscopy techniques. Numerical approximations can also be applied to obtain
theoretical predictions with the solution of the micromagnetism equations. Especially when it comes to
extensive arrays, whose objects have interactions, doubts arise about the effects of the dipole energy of
interaction between objects and the boundary conditions to be applied when solving the problem. When
micrometric objects are treated, several configurations of magnetization can appear within the elements
that make up the arrangement. In this work we present the fabrication of arrays of disks and ellipsoids
arranged in square order. The responses obtained in magnetization measurements with different external
field directions allow us to study how each arrangement behaves. The measurements were carried out by
applying an external magnetic field in the plane of the two-dimensional array and changing its
orientation in relation to the main directions. The objects obtained here were manufactured with optical
writing using the DWL66 system and deposition by Permalloy sputtering. The deposition of
magnetically soft material makes it easier to disregard magnetocrystalline anisotropy effects. Magnetic
measurements were performed using vibrating sample magnetometry (MAV) which reveals soft
ferromagnetic behavior at room temperature according to the simulations. The morphological
characterization of the samples were performed by optical microscopy and scanning electron microscopy
(SEM). For micromagnetic simulations we use the Object Oriented Micromagnetism Framework

(OOMMF) code to study the magnetization process of objects. The code is based on the Landau-Lifshitz-
Gilbert equation to simulate the configuration of magnetic moments and calculate the magnetization

energy of microstructures. The results are compared with the data obtained experimentally. Coercive
fields have an error of only 2%, possibly due to temperature considerations. The magnetization diagrams
show the presence of multiple magnetization mechanisms in this system.

BANKING MEMBERS:
Externo à Instituição - ALVARO ANTONIO OCHOA VILLA
Presidente - 2457389 - EDUARDO PADRON HERNANDEZ
Externo à Instituição - WELLINGTON MOREIRA DA SILVA
Externo à Instituição - YUSET GUERRA DAVILA