Study of magnetocaloric effect in anisotropic compounds RGa2 (R=rare earth)

• Grant number: 06/04659-3
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2007
• End date: September 08, 2008
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Flávio César Guimarães Gandra
• Grantee: Luzeli Moreira da Silva
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

In this project we propose the study of the magnetocaloric effect (MCE) in some magnetic anisotropic materials. The main focus isn’t the search for optimized entropy change (DS) or temperature variation(DT) values around ambient temperature but instead we aim to explore another form to obtain the MCE. The MCE is usually determined by the difference of entropy obtained by specific heat measurement in H=0 and H different of zero (usually between 2T and 7T). In fact, the MCE is obtained by magnetization measurements because some experimental difficulties to obtain the specific heat curves. However, in practice magnetic refrigerators requires the insertion and removal of the material in a magnetic field region. Another way to obtain the MCE is the utilization of the magneto-crystalline anisotropy of the material. The basic idea is rotate the single crystaline samples with ferromagnetic ordering and high anisotropy subjected to a magnetic field, which is alternately parallel to the easy or hard magnetic axis. For this work we propose the use of materials that we have previously studied (UGa2) mixing with other rare-earth wich will crystallize with the same structure and also presenting magnetic ordering. We intend to determine the MCE of (U1-xRx)Ga2 series in single crystalline form. The growth of single crystals will be a great achievement for our group. We will also make theoretical simulations in order to compare with the experimental results.