Magneto-transport and specific heat behavior of Cd-doped La0.5Ca0.5MnO3

The temperature-dependent magneto-tran sport properties and the specific heat of La-0.5(Ca0.5-xCdx)MnO3 (x = 0.0-0.5) are measured for understanding the electronic phase separation behaviors in manganites. It is surprising to observe that Cd-doping enhances the ferromagnetic metallic state and suppresses the insulating state. Two insulator-metal transitions in La-0.5(Ca0.3Cd0.2)MnO3 are observed, one occurs at temperature T-P1 in accordance with the observed paramagnetic-ferromagnetic transition point T-C and the other appears at a lower temperature T-P2. The magnetoresistance of La-0.5(Ca0.3Cd0.2)MnO3 as a function of temperature shows a sharp peak around T-C, and remains roughly unchanged over a wide temperature range below T-P1. It is argued that these fantastic properties are attributed to the coexistence of ferromagnetic metallic state and ferromagnetic insulating state under an anti ferromagnetic background due to the Cd-doping effect. (C) 2004 Elsevier B.V. All rights reserved.