C. Chaillout

Magnetic and Electric properties of La_{1-delta}MnO_{3}

The magnetic phase diagram of $La_{1-δ}MnO_{3}$ powdered samples have been studied as a function of $δ$ in the low doping range. $La_{0.97}MnO_{3}$ has a canted magnetic structure at low temperature $(θ\simeq 130\QTR{group}{{}^{\circ}})$. Above $T_{C}=118K$, it becomes a paramagnet with a huge effective magnetic moment, $μ_{eff}=6.0μ_{B}$, reflecting the presence of magnetoelastic polarons which are not affected by the magnetic field (up to 20T) nor the temperature $(1.2T_{C}<T<2.5T_{C})$. When $δ$ is increased to $δ=0.07$, polarons are still presen at high temperature, with a smaller size: $μ_{eff}=5.8μ_{B}$. The system becomes fully ferromagnetic below 170K but remains insulating down to the lowest temperature.