Effects of Cu and Fe doping on Raman spectra and on the structural and magnetic properties of ErMnO₃

Single phase ErMe_xMn_1-xO₃ (Me=Cu, Fe; 0≤x≤0.1) samples were synthesized by the solid state reaction method. The differences between the doping effects on the Raman spectra and on the structural, magnetic, and thermal properties of the two systems have been systematically investigated. In the ErCu_xMn_1-xO ₃ system, lattice parameter a increases with doping, while lattice parameter c decreases. It is more complicated in the ErFe_xMn _1-xO₃ system, where lattice parameter a decreases with doping, while lattice parameter c is enhanced after an initial slight decrease. Raman spectra show that the phonon peaks of ErFe_xMn _1-xO₃ slightly shift to higher frequencies with doping, while those of ErCu_xMn_1-xO₃ apparently shift toward lower frequencies. Heat capacity data indicates that the Néel temperature of ErMnO₃ is reduced to 61 K for ErCu _0.1Mn_0.9O₃ by Cu doping, whereas it is slightly enhanced to 79 K for ErFe_0.1Mn_0.9O₃ through Fe doping.