Effect of pressure and magnetic held on the resistance of the self-doped manganese perovskite La0.91Mn0.95O3

The effect of hydrostatic pressure P up to 9 kbar and applied magnetic fiel ds H up to 15 kOe on the transport properties of La0.91Mn0.95O3 at temperat ures T=77-300 K is reported. At ambient pressure and zero magnetic field th e transition to a ferromagnetic phase takes place at T(c)approximate to 252 K whereas a maximum in resistivity rho is observed at T-r = 262 K. It is s hown that the maximum in the derivative d rho (T,P)/dT occurs at the ferrom agnetic transition temperature T-c. The observed pressure coefficient d In Tc/dP approximate to0.0048 kbar(-1) is found to be consistent with Mn+4 con centration of about 40%. The observed behavior of the resistivity rho (T) a t applied magnetic field is analyzed by the mean field theory. It is shown that the maximum of d rho (T)/dT at applied magnetic field H shifts accordi ng to H-2/3.