相分离Nd_(0·5)Ca_(0·5)MnO_3体系的再入型自旋玻璃行为和电荷有序  

Reentering spin glass behavior and charge ordering in phase separation Nd_(0·5)Ca_(0·5)MnO_3 system

作　　者：俞坚[1] 张金仓[1] 曹桂新[1] 王仕鹏[1] 敬超[1] 曹世勋[1] 

机构地区：[1]上海大学物理系,上海200444

出　　处：《物理学报》2006年第4期1914-1920,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10274049);上海市教育委员会"曙光"计划(批准号:03SG35);上海市教育委员会重点学科建设计划(批准号:T0104)资助的课题.

摘　　要：研究了Nd_(0·5)Ca_(0·5)MnO_3体系的结构和输运特性.结构分析表明,在300K下,体系表现为O′型正交结构并存在典型的Jahn-Teller畸变.在8T磁场下,体系出现顺磁绝缘-铁磁金属的转变,庞磁电阻效应发生.磁测量发现,样品的奈尔温度TN和电荷有序转变温度TCO分别在150和240K左右,在41K左右出现典型再入型自旋玻璃行为,同时观察到了负的磁化率异常.结果表明,Nd_(0·5)Ca_(0·5)MnO_3体系在低温下存在着典型的相分离和多种复杂的磁相互作用竞争机制,这为强关联锰氧化物体系物理机制的理解提供了重要的实验资料.Half-doped manganese oxides are very important on clarifying physical mechanism of strong correlation electron system and colossal magnetoresistance （CMR） effect due to their rich physical content. The structure, electrical and magnetic transport properties of Nd0.5Ca0.5MnO3 manganite was systemically studied. The results show that Nd0.5Ca0.5MnO3 compound displays the O＇-orthorhombic structure and indicate the existence of the typical Jahn-Teller distortion under 300 K. The transport properties show that the system undergoes paramagnetic insulator-ferromagnetic metal transition under a magnetic field of 8 T and is accompanied by CMR effect, Meanwhile, it is found that the temperature of antiferromagnetic transition and charge ordering is around 150 and 240 K, respectively. There appears a typical reentrant spin glass behavior around 41 K and the negative magnetization is also observed in the compound. All these phenomena indicate that there exist several complex magnetic interactions in the ground state of this half-doped Nd0.5Ca0.5MnO3 compound at low temperature. The present results provide experimental data for strongly electronic correlated system of manganites.

关 键 词：庞磁电阻 自旋玻璃态 负磁化强度 电荷有序 

分 类 号：O482.5[理学—固体物理]