The renewed interest in doped manganate perovskites has been propelled by two new developments of the last decade: the ability to synthesize high quality thin film as well as single crystal forms of complex perovskite oxide materials, and the discovery of a large room-temperature magnetoresistance in thin film Lao.67Bao.33MnC>3. Soon after the report [1] of a 60% room temperature magne­ toresistance in thin film La o.67Bao.33Mn03, it was found [2-4] that a change of three order of magnitude in magnetoresistance can be obtained at 77 K in specially annealed thin films of Lao.67Cao.33Mn03. This phenomenon was since called “colossal magnetoresistance” effect, or CMR for short. The doped manganate perovskites was referred to as “CMR materials”.