Voltage-controlled colossal magnetoresistance in manganite/normal-metal heterostructures

It is well established that the resistivity of the manganites is a strong function of the magnetization. Near the ferromagnetic ordering temperature, colossal changes in the resistivity are seen in applied fields of several Tesla; such fields are too large for a number of potential applications. An alternative approach is to change the state of magnetization by injecting spin polarized carriers into manganite/classical ferromagnet heterostructures. In this work, results on manganite/normal-metal heterostructures in current perpendicular-to-plane geometry are reported. We observe a colossal magnetoresistance in fields of the order of 1 T which we attribute to magnetic interface scattering. The magnitude of this magnetoresistive effect can be controlled by the applied voltage, i.e., the heterostructures act as magnetic sensors with variable sensitivity. Implications of the interface resistance on spin injection from classical ferromagnets into manganites are discussed.