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Master's Dissertation
DOI
https://doi.org/10.11606/D.43.2019.tde-01022019-104912
Document
Author
Full name
Lina Ishida
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2019
Supervisor
Committee
Freitas, Rafael Sá de (President)
Carbonari, Artur Wilson
Pasca, Gabriel Adolfo Cabrera
Title in Portuguese
Antiferromagnetismo nos titanatos geometricamente frustrados Sm2Ti2O7 e Nd2Ti2O7
Keywords in Portuguese
antiferromagnetismo
frustração geométrica
pirocloro
titanatos
Abstract in Portuguese
Recentemente, observamos na comunidade científica o despertar de um interesse pelo estudo de lantanídeos com base em titânio; neste ínterim, as amostras Sm2Ti2O7 e Nd2Ti2O7 se destacam por terem sido pouco exploradas, especialmente a baixas temperaturas. Análises cristalográficas de monocristais de Sm2Ti2O7 e Nd2Ti2O7 nos permitiram confirmar inicialmente características de rede como a geometria cúbica e monoclínica, respectivamente, enquanto as análises magnéticas e calorimétricas forneceram a temperatura de transição, até então inédita no caso do Nd2Ti2O7 (aproximadamente T=0,62K), além de ordenamento do tipo antiferromagnético e presença de anisotropia a altas temperaturas, na amostra de Sm2Ti2O7, e por toda a extensão de temperaturas trabalhadas, na amostra de Nd2Ti2O7. Por fim, identificamos também a entropia esperada para spins do tipo Ising em ambas as amostras.
Title in English
Antiferromagnetism in the geometrically frustrated titanates Sm2Ti2O7 and Nd2Ti2O7
Keywords in English
antiferromagnetism
geometrically frustration
pyrochlore
titanates
Abstract in English
Recently the scientific community has shown interest for titanium lanthanides, with the titanates Sm2Ti2O7 and Nd2Ti2O7 being poorly approached, specially at low temperatures. Crystallographic analysis were performed on the single crystal samples of Sm2Ti2O7 and Nd2Ti2O7, which allowed us to confirm its expected cubic and monoclinic structures, respectively; Magnetic and calorimetric data displayed the transition temperature, not previously seen in case of Nd2Ti2O7, of T=0.35K and T=0.62K, respectively, and the antiferromagnetic behaviour of both samples; Anisotropy was observed at high temperatures on the Sm2Ti2O7 data and along all the temperature range studied for the Nd2Ti2O7 sample. Finally, we have identified the entropy of Ising spins on both samples.
 
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Publishing Date
2019-02-04
 
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