半掺杂Sm0.5Ca0.5MnO3体系的电荷有序和再入型自旋玻璃行为

研究了半掺杂锰氧化物Sm_0.5Ca_0.5MnO₃体系的结构、输运和磁特性，结果表明，在半掺杂情况下，该体系呈现O′类正交结构，表明体系存在典型的Jahn-Teller效应畸变；输运结果在整个测量温区均呈现半导体导电行为，没有出现金属－绝缘体(M-I)转变和CMR效应；电荷有序转变发生在T=270K左右，反铁磁转变温度出现在200K附近，且表现出典型的再入型自旋玻璃(spin-glass)行为，自旋玻璃转变温度T_SG在4关键词：自旋玻璃电荷有序负磁化现象多相竞争

Charge order phase and reentrant spin-glass behavior in half doped Sm0.5Ca0.5MnO3 manganite

The structure, transport and magnetic properties of half doped Sm_0.5Ca_0.5MnO₃ manganite has been systamatically studied. The results show that Sm_0.5Ca_0.5MnO₃ compound has the O′orthorhombic structure and shows typical Jahn-Teller distortion. Throughout the temperature range used, the electric transport shows semiconducting behavior and there are no I-M transition and CMR effect. Meanwhile, it is found that the charge-order and antiferromagnetic transition temperatures of the system are around 270K and 200K, respectively, whereas at lower temperature there appears a typical spin-glass state around 41K with reentrant behavior. The negative magnetization is also observed in this compound. All these phenomena indicate that for the ground state of Sm_0.5Ca_0.5MnO₃, there exists the competition mechanism of several complex magnetic interactions. Present study may provide abundant experimental information for understandig the mechanism of the strongly electron correlated system.