Decrease of the Curie temperature in La0.67Sr0.33MnO3 thin films induced by Au capping

Ferromagnetism of La0.67Sr0.33MnO3 is extremely sensitive to external perturbations like substrate-induced strain, charge injection and chemical interactions with neighbour layers. In this paper we discuss the perturbation induced by the presence of a metallic overlayer, typically deposited for electric contacts, in the prototypical case of the Au/La0.67Sr0.33MnO3 interface. In particular we found a sizable decrease of the Curie temperature in thin films of La0.67Sr0.33MnO3 after gold capping: 65 K for 5 nm thickness of the manganite. Apart from chemical reactions at the interface, charge injection-depletion induced by the difference in the work function between Au and La0.67Sr0.33MnO3 could partially explain this phenomenon.