Banca de DEFESA: DANIEL ANTUNES BARBOSA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : DANIEL ANTUNES BARBOSA
DATE: 17/05/2023
TIME: 14:00
LOCAL: campus VI
TITLE:

EXTRACTION CURVES ADJUSTMENT MODELS FOR MAGNETIZATION CALCULATION USING THE SQUID CRYOGENIC S700X MAGNETOMETER SOFTWARE

KEY WORDS:

Magnetic characterization; Extraction plot; SQUID magnetometer.

PAGES: 40
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Físico Química Inorgânica
SUMMARY:

The growing interest, mainly in solid state physics, for the characterization of small samples or weakly magnetic samples, such as thin films, led to the development of measuring equipment technology whose state of the art is concentrated in equipment equipped with SQUID sensors (quantum interference device superconductor). In high-sensitivity magnetization measurements, some deviations in the measurements are common and may occur due to several factors, among which we can highlight the deviations resulting from the size and geometric shape of the sample, effects on the structure of the sample, uncontrolled displacement of the sample in the sample holders, effects of thermal expansion and contraction of the sample holder set, magnetic noise from different sources, among others. In this research, we magnetically characterized a sample of Dy2O3 dysprosium oxide, on which magnetization measurements were performed in a SQUID magnetometer as a function of the applied magnetic field, as well as magnetization measurements as a function of temperature variation. In this second type of measurement, measurements are generally carried out over a wide temperature range (5K to 300K), this causes the sample holder and the rod that supports the sample holder to undergo thermal expansion or contraction effects, causing that the sample leaves the correct position in which it was initially placed and due to this the measurement presents a deviation. The software that controls the equipment has three methods for the treatment of magnetization data extraction measurements. These methods were studied in order to verify which one would best suit the problems presented in the measurements, such as those described above, in particular the deviation due to thermal expansion or contraction. The standard adjustment method of the software (Multipol) in its fourth degree was sufficient to remove the deviation related to the contraction/expansion of the sample holder set. The FITRMS method was also studied, which had to be previously calibrated. With this adjustment method it was also possible to remove deviations in the measurements due to the thermal expansion effect that occurs in the sample holder set.

COMMITTEE MEMBERS:
Presidente - EMERSON FERNANDES PEDROSO
Interna - PATRICIA SANTIAGO DE OLIVEIRA PATRICIO
Externo à Instituição - LUCIANO RONI SILVA LARA - UFSC