Crystal, spin glass, Griffiths phases and magneticaloric properties of the Sr1.5Nd0.5MnO4 compound

The Sr1.5Nd0.5MnO4 compound was synthesized by the solid state reaction method. The X-ray diffraction (XRD) and magnetic measurement have been used to study the physical and chemical properties of the Sr-1.5Nd0.5MnO4 compound. The XRD data has been analyzed by Jana refinement technique. The refinement has revealed that the compound crystallizes in tetragonal symmetry with Pmmm space group. The magnetic properties of polycrystalline Sr1.5Nd0.5MnO4 compound are discussed in detail, based on the magnetization, susceptibility, and isotherm. The specimen presents a ferromagnetic(FM) property with T-C = 245 K, and a Griffiths phase at T-G = 275 K which gives as the existence of ferromagnetic clusters in the paramagnetic domain. A big divergence between zero fields cooled (ZFC) and field cooled (FC) M (T) is observed at low temperature below of blocking temperature. This indicated a thermomagnetic irreversibility behavior. In addition, the zero field cold (ZFC) curve shows a clear cusp at low temperature (35K) which is generally related to a spin glass or a cluster-glass state. The variation of magnetocaloric Delta S-M as function of magnetic field (mu H-0) has deduced that the compound Sr1.5Nd0.5MnO4 obeys the mean field. According to the variation of resistivity as a function of temperature, the compound presents a semiconductor behavior. The electric transport behaviors obey to variable range hopping model. From this model, we can determinate the increase of activation energy E-a when the temperature increases. (C) 2013 Elsevier B.V. All rights reserved.