Effect of Cr substitution at Mn sites on magnetic and transport properties in charge ordered NdosCaasMni.xCrxOa (x = 0,0.02, 0.05) manganites / Zainab Mohamad Asri

Charge ordered Ndo.5Cao.5Mni.xCrx03 (x - 0, 0.02, 0.05) have been investigated using electrical resistivity and magnetic susceptibility to explain the effect of Cr substitution on electrical transport and magnetic properties. Electrical resistivity and magnetic susceptibility measurements showed that the x = 0 sample exhibits an insulating behavior and an anti-ferromagnetic (AFM) transition at 230K which can be related due to Mn3+ - O2" - Mn4+ interaction. With increasing of Cr content, a metal-insulator (MI) was observed and the transition shifted to higher temperature from TMI ~ 133K (x = 0.02) to TMI ~ 136K (x = 0.05) accompany with the ferromagnetic (FM) transition which is observed around Tc ~ 148K and Tc ~ 152K for x = 0.02 and .x=0.05 respectively. This can be suggested to be due to the double exchange (DE) mechanism of Mn3+ - O " - Mn4+. Apart from that, the magnetic susceptibility and resistivity measurement indicated the existence of charge ordering (CO) state at a sharp peak. With increasing Cr substitution, the CO states weakened due to weakening of Jahn Teller (JT) effect.