High pressure synthesis and study of magnetic and transport properties of Pb-substituted manganites with perovskite structure

The stoichiometric La1 − xPbxMnO3 (x ⪯ 0.6) and La0.56Pb0.44MnO2.56F0.44 as well as nonstoichiometric La1 − xPbxMnO3 − y (x ⪯ 0.44) solid solutions with perovskite structure have been obtained under high pressure conditions. It was demonstrated that these compounds are ferromagnetic in a wide range of Pb concentrations and exhibit large magnetoresistance in spite of the absence of Mn4+ ions. It is supposed that magnetic ordering in these materials is governed by superexchange interaction via oxygen.