Pressure effect on magnetic and transport properties of Zn doped La0.91Mn0.95O3 manganite

The effect of hydrostatic pressure P up to 1 GPa and applied magnetic fields H up to 1.5 T on the magnetic and transport properties of La0.91Mn0.95O3 doped with 7 at. % Zn at the temperature range of 15-350 K is reported. It was found that the doping by Zn changes the low temperature conductance from a metallic-like to a nonmetallic one. Doping by Zn of the initial self-doped sample shifts the Curie temperature from 252 to 204 K. In both compounds the applied pressure enhances the ferromagnetic coupling and Curie temperature. The pressure coefficients of the Curie temperature are equal for both compounds being dT(C)/dP approximate to 13 K/GPa. Above the Curie temperature the resistivity of Zn-doped manganite obeys Mott's law rather than the Arrhenius behavior. Both parameters, A and T-0 of Mott localization law decrease under pressure indicating a reduction in the localization energy. (C) 2001 American Institute of Physics.