In strongly correlated electronic systems, such as manganites, the globaltransport behavior depends sensitively on the spin ordering, whose alterationoften requires a large external magnetic field. Here we show that the spinordering in manganites can be easily controlled by exchange field across theinterface between a ferromagnet and a manganite. By depositing isolatedferromagnetic nanodots on a manganite thin film, we find that it is possible toovercome dimensionality and strain effects to raise the metal-insulatortransition (MIT) temperature by over 200 K and increase the magnetoresistanceby 5000%. The MIT temperature can also be tuned by controlling the density ofthe magnetic nanodots which indicates that the formation process of electronicphase separation can be controlled by the presence of magnetic nanodots.
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