Impact of non-magnetic Zn2+ doping on the structural, magnetic and magnetocaloric properties of Nd0.5Ca0.5Mn1-xZnxO3 (x = 0, 0.05, 0.10) compounds

Abstract

Nd0.5Ca0.5Mn1-xZnxO3 (x = 0, 0.05, 0.10) polycrystalline perovskite samples were made using the conventional solid-state reaction method to investigate effects of Zn2+ substitution on the structural and magnetic properties, along with exchange bias and magnetocaloric effects. All the bulk compounds belong to Pnma space group with orthorhombic structure. Both charge ordering temperature (TCO) and antiferromagnetic ordering temperature (TN) decreased with increase in Zn concentration. Thermal irreversibility in magnetization in all Zn doped samples indicate a first-order phase transition. At low temperatures soft ferromagnetic nature was observed from the isotherms (M(H)). Field-induced metamagnetic behavior was observed in low-temperature regions. Increasing exchange bias effect with Zinc doping was observed, which reduces with temperature due to thermal fluctuation. Also magnetocaloric effect (MCE) has been calculated for two temperature regimes, 10–65 K and 150–300 K. As observed in temperature-dependent magnetization plot entropy-change parameter switches from negative (above TCO) to positive (below TCO), accompanied by a change in magnetic correlation from ferromagnetic to antiferromagnetic. However, the magnitude of change in entropy decreases with Zn doping, whereas, the same increases at low-temperature region. The destabilization of the CO state and enhanced disorder by the Zn doping plays role behind this variation in MCE behavior.