Mazur A. NMR spectroscopy of inhomogeneous ferromagnetic state of manganites

The work is devoted to experimental research of the inhomogeneous ferromagnetic (FM) state of manganites La1-xSrxMnO3+delta with the aim of establishment of the FM insulating state. Is it shown that the basic FM state of series of the polycrystalline samples La1-xSrxMnO3+delta (х=0, 0.075 and 0.125) at low temperatures is inhomogeneous and consists of two phases, each of which is characterized by the own type of conductivity the FM conducting and FM insulating. It is shown that each of coexisting phases, are also inhomogeneous and can be divide into two phases different in terms of the local hyperfine interactions. It is found, that at decrease to the nanopowders size of the systems La0.7Sr0.3MnO3 there is a limit (~10 nm), less which phase separation of FM metallic phase is not observed. In addition, the increases of external high hydrostatical pressure significantly decrease the size of FM conducting phase specific resistance and poorly increase the volume of this phase.