Cu/Mn Doped EuMnO₃:Synthesis,Structure And Magnetic Property

Multiferroics is a novel class of materials which can simultaneously show two or all three of the primary ferroic properties（ferromagnetism, ferroelectricity, and ferroelasticity） in the same phase. Due to the magnetoelectric coupling between ferroelectric and magnetic ordering, multiferroic materials are a promising family with great potential applications, such as multistate memory elements and magnetic field sensors. EuMnO₃ is kind of typical orthorhombic pervoskite manganese compound, which had been attributed to a phase transition from PM to ICAFM（incommensurate antiferromagnetic） at ⁵0K and a further transition from ICAFM to c AAFM（canted A-type antiferromagnetic） ordering at ⁴4 K. As its phase transition temperature is too low to apply in practice. In this thesis, so as to improve the key drawback of EuMnO₃, the doping effects on EuMnO₃ compound is systematically investigate through Cu doping at Mn site and Mn doping at Eu site of EuMnO₃. All the compounds were prepared by the solid state reaction method. The main points as follows:1. As for single phase Eu Mn_1-xCu_xO₃-δ（0≤x≤0.3） compounds, the doping effect on the crystal structure and magnetic properties were systematically studied. The solid solution can be indexed to the orthorhombic structure with the Pnma space group. Rietveld refinement indicates that a and b lattice parameter decreases and the c lattice parameter increases with increasing Cu concentration. Magnetic susceptibility measurements show that the two magnetic transitions for these materials occur from 57 to 22 K and 45 to 20 K, respectively. The Curie constant and effective magnetic moment decrease with increasing Cu concentration.2. In the single phase orthorhombic(Eu_1-xMn_x)MnO₃（0≤x≤0.125） system, lattice parameters a and c decrease with doping Mn and lattice parameters b increases with increasing Mn. The magnetic susceptibility data show that with increasing the Mn content, the magnetic phase transition temperature significantly increasing.