Magnatic field induced phase transition and transport properties in phase separated Eu0.5Sr0.5MnO3 system

The structure，electrical and magnetic properties of the half doping phase separated Eu0.5Sr0.5MnO3 manganite have been systematically studied. The results show that Eu0.5Sr0.5MnO3 compound has the O′ orthorhombic structure and shows typical Jahn-Teller distortion. It is found that ferromagnetic phase turn up near 75 K and evident split of field cooling （FC） and zero field cooling （ZFC） under 4000 A/m is observed around 42 K. The ac susceptibility curve shows also a sharp peak around 42 K，indicating cluster-glass state rather than a spin glass state at 42 K. Meanwhile，throughout the measuring temperature range，the electric transport shows insulating behavior and there is no insulator-metal （I-M） transition. However，an applied magnetic field of 1.6×105 A/m can induce I-M transition. The conducting behavior of Eu0.5Sr0.5MnO3 is well fitted by the Mott variable range hopping （VRH） model. All these phenomena indicate that for the ground state of Eu0.5Sr0.5MnO3，there exists the competition mechanism of several complex magnetic interactions. The study provides abundant experimental information to underdtand the mechanism of the strongly electron correlated system.