Magnetic and electrical properties of layered perovskite La1.3Sr1.7Mn1-xCuxO7
层状钙钛矿La1.3Sr1.7Mn2-xCuxO7的磁性及电特性

Magnetic and electrical properties of polycrystalline La1.3Sr1.7Mn2-xCuxO7 prepared by solid state reaction were investigated. The X-ray diffraction pattern shows that the two samples have Sr3Ti2O7 type perovskite structure. The two samples undergo complex transition with lowering temperature. The x=0 samples, have the two-dimensional short-range ferromagnetic order at T*=231 K and then transform to the three-dimensional long-rangs ferromagnetic state at TC=114 K, at last they enter the canted antiferromagnetic state at TN=56K. The T*, TC and TN are all reduced at the 5% Cu doping level. Additionally, the two samples exhibited two distinct resistivity peaks, which is due to coexistence of the two phases. The metal-insulator transition temperature was decreased but the magnetoresistance was enhanced at the 5% Cu doping level.