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Tuning the metal-insulator transition in manganite films through surface exchange coupling with magnetic nanodots

In strongly correlated electronic systems, such as manganites, the global transport behavior depends sensitively on the spin ordering, whose alteration often requires a large external magnetic field. Here we show that the spin ordering in manganites can be easily controlled by exchange field across the interface between a ferromagnet and a manganite. By depositing isolated ferromagnetic nanodots on a manganite thin film, we find that it is possible to overcome dimensionality and strain effects to raise the metal-insulator transition (MIT) temperature by over 200 K and increase the magnetoresistance by 5000%. The MIT temperature can also be tuned by controlling the density of the magnetic nanodots which indicates that the formation process of electronic phase separation can be controlled by the presence of magnetic nanodots.