Room Temperature Ferromagnetism in Sm0.5Sr0.5CoO3 Thin Films Deposited by Pulsed Laser Deposition

Ferromagnetic Sm0.5Sr0.5CoO3 thin films were deposited on MgO/TiO2/SiO2/Si (MgO) and Pt/InO2/SiO2/Si (Pt) substrates by pulsed laser deposition. The crystallinity and morphology of the films were characterized by X- ray diffraction and field emission scanning electron microscopy, respectively. The electrical properties revealed metallic- like behavior at room temperature, confirming the transition from the metallic state to the insulating state at T > 300 K. The magnetization as a function of the temperature under the zero-field-cooled and field cooled modes for the Sm0.5Sr0.5CoO3 confirm that the Curie temperature higher than 300 K for the films deposited on the MgO substrate. The M-H hysteresis loops show that both films exhibit hard ferromagnetic behavior at 10 K independent of substrate type. However, the films deposited on the MgO substrate show a soft ferromagnetic state, whereas those on the Pt substrate exhibit an antiferromagnetic state at 300 K. The correlation between the ferromagnetic and metal states depending on the double exchange interaction and spin states transition at low and high temperatures is discussed.