The A-site ordered perovskite oxides with chemical formula AA03B4O12 display many intriguing physical properties due to the introduction of transition metals at both A0 and B sites. Here, research on the recently discovered intermetallic charge transfer occurring between A0-site Cu and B-site Fe ions in LaCu3Fe4O12 and its analogues is reviewed, along with work on the magnetoelectric multiferroicity observed in LaMn3Cr4O12 with cubic perovskite structure. The Cu–Fe intermetallic charge transfer (LaCu3+3 Fe3+4 O12→LaCu2+3 Fe3.75+4 O12) leads to a first-order isostructural phase transition accompanied by drastic variations in magnetism and electrical transport properties. The LaMn3Cr4O12 is a novel spin-driven multiferroic system with strong magnetoelectric coupling effects. The compound is the first example of cubic perovskite multiferroics to be found. It opens up a new arena for studying unexpected multiferroic mechanisms.
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