Banca de DEFESA: ARTHUR LANNE RICARDO DE SOUZA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ARTHUR LANNE RICARDO DE SOUZA
DATE: 28/07/2023
TIME: 09:00
LOCAL: online
TITLE:

Using Ti1−xCux thin films as temperature sensors applied for the study of the Anomalous Nernst Effect in multilayer
ferromagnetic structures

KEY WORDS:

Anomalous Nernst Effect, Ti1−xCux, Thin Films, Temperature Sensors, Applicability, Integrated systems

PAGES: 112
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

Nowadays, it is increasingly necessary to develop clean energy sources as well as energy-efficient electronic devices. In this
context, the Anomalous Nernst Effect (ANE) has the potential for energy-efficient and sustainable integrated systems
applications. This work presents a proposal for the applicability of the thermal sensorial properties of the alloy Titanium-
Copper (TiCu) integrated into nanostructured ferromagnetic systems for the study of the Anomalous Nernst Effect. For this
purpose, we produced and investigated the ability of Ti1−xCux thin films to act as temperature sensors based on the variation of
electrical resistance (RTD sensors). We used the magnetron sputtering technique to deposit Ti1−xCux films in three
compositions: Ti0.74Cu0.26, Ti0.70Cu0.30, and Ti0.54Cu0.46. We tested the performance of Ti1−xCux films produced as a potential
temperature sensor through temperature variation protocols in the range between 35 and 110 °C. Among the compositions
produced, the film Ti0.70Cu0.30 showed the most promising results. The Ti0.70Cu0.30 film showed linearity and stability in the
thermoresistive response, as well as excellent thermal sensitivity, quantified by the TCR coefficient α. The α obtained for the
film Ti0.70Cu0.30 was −1.99 × 10−3°C−1. We integrated the Ti0.70Cu0.30 film into a TiCu/Insulator/NiFe multilayer ferromagnetic
nanostructure and compared it with a TiCu/NiFe nanostructure to study the influence of the insulating layer, especially on the
magnetic behavior. As an insulating material, we use Kapton. Both samples showed soft magnetic behavior, characterized by
low values of the coercive field (Hc) and saturation field (Hs). The presence of the insulating layer influenced a slight
difference in the coercivity of the multilayer structures, for TiCu/Isolate/NiFe Hc ≈ 5 Oe and for TiCu/NiFe Hc ≈ 9 Oe, due to
the flexibility of the surface of the Kapton better accommodated the particles during the deposition process. However, in
practice, the magnetic behavior of the two structures is similar. We investigated the Anomalous Nernst Effect through the
voltage VANE, using three values for the applied temperature gradient ∇T. The voltage VANE of the samples showed smooth
behavior as a function of the magnetic field, with low coercivity and saturation field, as well as the magnetic behavior. The
TiCu sensor was able to read the temperature variations during all stages of the voltage measurement process VANE in both
samples for the three values of ∇T. We calculated the Anomalous Nernst Coefficient (SN) for the TiCu/Insulator/NiFe sample,

where we obtained SN = 0.60 μV/K, and for the TiCu/NiFe sample, SN = 0.46 μV/K. These values are in agreement with SN
values reported in the literature for NiFe monolayer structures at room temperature. Therefore, Ti0.70Cu0.30 film is an excellent
candidate to act as an RTD-type temperature sensor, with potential applicability in different systems.

COMMITTEE MEMBERS:
Externo à Instituição - ALEXANDRE DA CAS VIEGAS
Externo à Instituição - DANNIEL FERREIRA DE OLIVEIRA
Interno - 1508681 - FELIPE BOHN
Interno - 2492756 - JOAO MEDEIROS DE ARAUJO
Presidente - 1474380 - MARCIO ASSOLIN CORREA
Interno - 1788659 - MATHEUS GAMINO GOMES