Banca de DEFESA: ADLAN DA SILVA FREITAS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ADLAN DA SILVA FREITAS
DATA : 26/10/2023
HORA: 14:00
LOCAL: Sala virtual
TÍTULO:

Magnetocaloric effect on clusters of ferromagnetic nanoparticles

PALAVRAS-CHAVES:

Magnetocaloric effect, Nanoparticles, Clusters, Dipolar Field, Entropy Change.

PÁGINAS: 70
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
SUBÁREA: Física da Matéria Condensada
ESPECIALIDADE: Materiais Magnéticos e Propriedades Magnéticas
RESUMO:

The magnetocaloric effect (MCE) is a relevant subject of study due to its potential in areas like biotechnology, medicine, and materials engineering. When a magnetic material is subjected to an external magnetic field, its entropy changes. Upon removal of the field, the material undergoes a temperature change, referred to as the magnetocaloric effect. This phenomenon has several innovative applications, such as magnetic refrigeration, magnetic hyperthermia, and data storage.

Magnetic refrigeration is a promising application of the EMC effect due to its eco-friendly nature. It offers a sustainable and efficient alternative to traditional refrigeration methods that rely on harmful gases. This technology has a significant impact, and with increasing concerns about the environment, it provides an excellent solution to the refrigeration needs of various sectors.

Currently, research is focused on discovering new materials and magnetic structures that efficiently present Electromagnetic Compatibility (EMC). Therefore, it is crucial to comprehend the interactions among magnetic moments, temperature, and external fields, as well as the magnetic order of magnetic materials concerning intrinsic and extrinsic parameters, to develop new structures that meet the demands of modern society.

This study aims to investigate the magnetocaloric effect on clusters of ferromagnetic gadolinium (Gd) nanoparticles with ellipsoidal geometry. Additionally, the study will explore the influence of the dipolar field on the thermal stabilization of the magnetic moments of the nanoparticles.

This study analyzed micrometric elliptical clusters of Gd nanoparticles with varying eccentricities, nanoparticle densities, and diameters ranging from 30 nm to 200 nm. The dipolar interaction in the clusters depends upon their anisotropy, which is influenced by their geometry. The analysis was conducted at a fixed magnetic field in the preferred direction of anisotropy (i.e., the ellipse's major axis) in a temperature range of 200 K to 450 K. The isothermal magnetic entropy variation DS_M was calculated under an applied external magnetic field, revealing the normal EMC and the inverse magnetocaloric effect (EMCI) due to the competition between the Zeeman and dipolar interaction energies. Transitional phrases were used to indicate the sequence of the analysis. The technical terms planar susceptibility and out-of-plane angle were also utilized.

MEMBROS DA BANCA:
Presidente - 330.140.197-04 - ARTUR DA SILVA CARRIÇO - UFRN
Interno - 635.107.314-68 - IDALMIR DE SOUZA QUEIROZ JÚNIOR - UFERSA
Externo à Instituição - GUSTAVO DE OLIVEIRA GURGEL REBOUÇAS - UFERSA