Abstract
"Nanocrystalline double layered La1.2R0.2Ca1.6Mn2O7 manganites with R = Tb, Dy, Ho, and Er were synthesized by sol-gel method. The XRD measurements indicate that all samples are single phase with a Sr3Ti2O7-type tetragonal (I4/mmm) structure and mean crystallite sizes between 22 nm and 27 nm. The magnetic measurements evidence a spin-glass like behavior at low temperatures for all samples, which may be due to frustration of random competing ferromagnetic and antiferromagnetic interactions together with the anisotropy originating from the layered structure. A moderate magnetocaloric effect was found for all samples, with the maximum entropy change located at temperatures near the magnetic transition ones, but high RCP(S) values were obtained due to the broadened magnetic entropy curves. Keywords: nanoparticles, double layered perovskite, magnetocaloric effect. "
Reference22 articles.
1. "[1] Y. Moritomo, A. Asamitsu, H. Kuwahara, Y. Tokura, Nature 380, 141-144 (1996).
2. [2] H. Asano, J. Hayakawa, M. Matsui, Phys. Rev. B 56, 5395 (1997).
3. [3] H. Asano, J. Hayakawa, M. Matsui, Appl. Phys. Lett. 70, 2303 (1997).
4. [4] N.H. Hur, J.T. Kim, K.H. Yoo, Y.H. Park, J.C. Park, E.O. Chi, Y.U. Kwon, Phys. Rev B 57, 10740 (1998).
5. [5] T. Kimura and Y. Tokura, Annu. Rev. Mater. Sci. 30, 451 (2000).