Structure and magnetic properties of perovskite manganites La2/3Sr1/3FexMn1-xO 3

Abstract

Perovskite manganites with nominal composition La2/3Sr1/3FexMn1-xO3 (x=0, 0.1, 0.2, 0.3, 0.5) are prepared by the sol-gel method. The samples are treated three times at 773 K, 873 K and 1073 K, separately, in which processes the temperature is slowly increased. The X-ray diffraction patterns indicate that the samples have a single phase and perovskite structure each. The dimensions of the crystalline particles, lattice constants, cell volumes of the samples are calculated using the XPert HighScore Plus software. The magnetic properties are measured using a Quantum Design Physical Property Measurement System. The magnetic moments of the samples at 10 K decrease with the increase of Fe doping level x. The decreasing process can be divided to two ranges: one is from x=0 to x=0.2, in which range the average magnetic moment per formula decreases rapidly from 2.72 B to 0.33 B, while the Curie temperature decreases rapidly from 327 K to 95 K, i.e., it is reduced by 232 K; the other is from x=0.2 to x=0.5, in which range, however, the average magnetic moment per formula decreases slowly from 0.33 B to 0.05 B, while the Curie temperature decreases slowly from 95 K to 46 K, i.e., it is reduced only by 49 K. The experimental result that the magnetic moments of the samples decrease with the increase of Fe doping level may be explained as the fact that the magnetic moment direction of the Fe cations is opposite to those of Mn cations.