Banca de QUALIFICAÇÃO: MATEUS SOUZA DUTRA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : MATEUS SOUZA DUTRA
DATE: 25/07/2023
TIME: 14:00
LOCAL: Bloco A Sala R602-3
TITLE:

EuZn2P2: From Topological Insulator to Emergent States

PAGES: 50
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUBÁREA: Física da Matéria Condensada
SPECIALTY: Ressonância Mag. e Relax. na Mat. Condens; Efeitos Mosbauer; Corr. Ang. Pertubada
SUMMARY:

Topological insulators are a class of materials that have metallic states on the surface, while their bulk behaves as an insulator. These systems consist of materials that have a non-trivial topological order, causing them to have different behaviors when observed on their surface or inside. Europium-based intermetallic compounds are widely studied nowadays due to the number of phenomena and properties that can emerge in these materials, including topology effects. EuZn2P2 was recently classified as a topological material that has an antiferromagnetic ordering temperature of TN= 23 K, an accessible temperature when compared to compounds of the same EuT2P2 family (T = transition metal). The crystal structure of EuZn2P2 is of the CaAl2Si2 type, belonging to the P-3m1 space group which consists of a trigonal space group. In this work we present an initial characterization of EuZn2P2, which consisted of x-ray diffraction (XRD) measurements, electronic x-ray energy scattering spectroscopy (EDS), specific heat and magnetization. Mossbauer spectroscopy and electronic paramagnetic resonance measurements were also carried out where, through the adjustments of the Mossbauer spectra, we determined that the magnetic moments of EuZn2P2 are outside the plane [100] by an angle θ∼51º. We also found evidence of a possible crystallographic change in the Eu sites, or even a possible reorientation of the electric field gradient (EFG) in relation to the hyperfine field. Measurements of specific heat as a function of temperature show the signature of the antiferromagnetic transition at TN = 23 K and allow the calculation of the magnetic entropy of the system, which reaches S(TN) ∼ 9.9 J.mol−1.K−1, lower than the expected value of 17.2 J.mol−1.K−1. Using the Curie-Weiss analysis on the susceptibility curves, we found an effective moment of p_ef= 7.00 for H||c and p_ef= 7.00 for H⊥c, close to the expected values for Eu2+, with S= 7/2. This work aims to present the results obtained for the compound EuZn2P2, with the purpose of carrying out possible identifications and indications of emerging phases in this material. The relevance of the study is due to the fact that several works demonstrate the topological properties of this system, which may have potential applications in the technology industry.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 2605463 - JOSE ANTONIO SOUZA
Membro Titular - Examinador(a) Interno ao Programa - 2249395 - THIAGO BRANQUINHO DE QUEIROZ
Membro Titular - Examinador(a) Externo ao Programa - 1675617 - EDUARDO PERES NOVAIS DE SA
Membro Suplente - Examinador(a) Interno ao Programa - 1734908 - FABIO FURLAN FERREIRA