Magnetic and magnetocaloric properties of Gd3−xTbxGa5O12 (x=0, 1, 2, 3) garnets

• Published in: Journal of magnetism and magnetic materials 2012-06, Vol.324 (12), p.1962-1966
• Main Authors: Reshmi, C.P., Savitha Pillai, S., Suresh, K.G., Varma, Manoj Raama
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Arrott plot; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Effective magnetic moment; Entropy; Exact sciences and technology; Garnets; Magnetic moment; Magnetic properties; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Magnetization; Magnetocaloric effect; Magnetocaloric effect, magnetic cooling; Order disorder; Physics; Rare earth garnet; Rare earth metals
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2012.01.030

The structure and magnetocaloric properties of Tb substituted Gd3Ga5O12 garnets have been investigated. The structural refinement of X-ray diffraction patterns show that Gd3−xTbxGa5O12 (x=0, 1, 2, 3) are isostructural, with the symmetry of a cubic space group Ia3¯d. The temperature dependence of magnetization studies indicate that all the samples follow Curie–Weiss paramagnetic behavior above 25K and the effective magnetic moment increases with Tb concentration. The low temperature magnetization studies suggest that there exists a field dependent antiferromagnetic ordering of rare earth ions in Tb substituted Gd3Ga5O12, which in turn leads to a lower magnetic moment in Gd3−xTbxGa5O12 (x=1, 2, 3), compared to that of Gd3Ga5O12. Magnitude of field corresponding to the antiferromagnetic ordering is found to be dependent on temperature as well as on Tb concentration. Magnetocaloric effect analysis confirms that Tb substitution enhances the magnetic entropy change at higher temperatures and Gd3−xTbxGa5O12 (x=1, 2, 3) are better candidates than Gd3Ga5O12 for low fields and low temperature magnetic refrigeration applications. ► Structural and magnetic characterizations of Tb substituted GGG were done. ► Lattice parameters and effective magnetic moments show a systematic trend on Tb substitution. ► Arrott plots show the exchange coupling strengths between the rare-earth moments in GGG & TGG at low temperature region. ► Tb substituted materials show enhanced MCE than GGG for low fields at low temperatures. ► Field dependant entropy change was studied for each material.