A study on the magnetic properties of Gd-Sr based low bandwidth manganites in their bulk and thin film forms and evidence for magnetization reversal in bulk Gd0.7Sr0.3MnO3

A study on the magnetic properties of both bulk and thin film forms of charge ordered Gd-Sr manganites belonging to the series Gd1−xSrxMnO3 (x=0.3, 0.5, 0.6) was performed. In the case of bulk, it is found that the Gd moments order antiparallel to the manganese spins giving rise to a ferrimagnetic behavior. A spin glass transition due to the competing ferromagnetic (FM) and antiferromagnetic (AFM) interactions is observed at around 42 K. Bulk form of Gd0.7Sr0.3MnO3 exhibits magnetization reversal for applied fields of 25 Oe and 50 Oe at very low temperatures. In Gd1−xSrxMnO3 thin films, coercivity is found to be lower when compared to their bulk counterparts. Thin film Gd0.7Sr0.3MnO3 exhibits both glassy and ferrimagnetic behavior for an applied magnetic field of 200 Oe similar to bulk. While for x=0.5 and 0.6, coercivity is lower and therefore the applied magnetic field of 200 Oe is large enough to suppress both the glassy and ferrimagnetic phases in thin films. Reduced coercivity of thin films when compared to bulk has been attributed to the grain size effect.