SINGLE-CRYSTAL GROWTH AND PROPERTIES OF THE DOUBLE-LAYERED MANGANESE OXIDES

The giant-magnetoresistance cubic perovskite oxides of the type RMnO3 (R = rare earth) can be tailored by layering with additional MnO2 shee ts. The layered manganese oxides, (R, Sr)(n+1)Mn3n+1, produce variants that adopt the K2NiF4 structure for n = 1 and n = 2 similar to that o f the high-T-c cuprates, and exhibit interesting properties. Single cr ystals of the two-layer (n = 2) perovskites of the type (R, ST)(3)Mn2O 7 (R = Nd, Pr) have been grown by the floating-zone method using an in fra-red image furnace. Large crystals could be cleaved from the boules grown.