Non-Magnetic doping effects on magnetic properties of High-Temperature multiferroic compounds YBaCu1-xZnxFeO5 and YBaCuFe1-yGayFeO5

Abstract

This study examines the effects of non-magnetic impurities at different magnetic sites on the magnetic properties of the ordered oxygen-deficient perovskite YBaCuFeO₅, which exhibits multiferroic behavior above room temperature. Magnetic susceptibility measurements were performed on polycrystalline samples of YBaCuFe_1-yGa_yO₅ with Ga³⁺ (spin S = 0) doping at Fe³⁺ (S = 5/2) sites and YBaCu_1-xZn_xFeO₅ with Zn²⁺ (S = 0) doping at Cu²⁺ (S = 1/2) sites. Magnetic susceptibility (χ)–temperature (T) curves for both doped systems below 50 K did not demonstrate Curie-like behavior indicative of a paramagnetic component, suggesting that free-end spins were not induced by long-range interactions in the systems. From the peak temperatures of the χ–T curves, the doping concentration dependence of the magnetic transition temperatures T_N1 and T_N2 was determined. For YBaCuFe_1-yGa_yO₅, both T_N1 and T_N2 decrease linearly with increasing y. In contrast, for YBaCu_1-xZn_xFeO₅, T_N1 decreases while T_N2 increases with increasing x , with T_N2 reaching a maximum value at 349 K at x  = 0.09. Although the atomic arrangement of Cu²⁺ and Fe³⁺ ions is randomly distributed within (Cu, Fe)O₅ oxygen pyramids, these results indicate that Cu²⁺ and Fe³⁺ ions play distinct roles in determining the magnetic properties. Based on these experimental findings, a discussion is provided on the physics of non-magnetic impurity effects to different magnetic ions for the high-temperature multiferroic compound YBaCuFeO₅.