Impact of strain on metamagnetic transitions in Sm0.5Sr0.5MnO3 thin films

Abstract

Sm0.5Sr0.5MnO3 thin films were deposited by DC magnetron sputtering on LaAlO3 (LAO) and SrTiO3 (STO) substrates. The film on LAO, which is under compressive strain, undergoes paramagnetic–ferromagnetic (PM–FM) transition at TC ∼116 K and shows insulator-metal transition (IMT) at TIM ∼ 115 K. The film on STO is under tensile strain and has TC ∼ 112 K; and shows IMT at TIM ∼ 110 K. Around ∼80 K, the film on STO shows a broad peak in the resistivity that could be seen as the reentrant IMT due to appearance of a metamagnetic state, the presence of which is confirmed by the discontinuous irreversible jumps in the magnetic field dependent isothermal resistivity at T < 85 K. These signatures of the metamagnetic state are not seen in the film on LAO. The occurrence and absence of metamagnetic state in films on STO and LAO, respectively, has been explained in terms of the control of the competing FM metallic and antiferromagnetic–charge ordered insulating (AFM–COI) phases by the different strain states in these films.