掺杂锰氧化物和极化子行为  

Doped manganites and polaron behavior

作　　者：熊光成[1] 

机构地区：[1]北京大学物理学院,北京100871

出　　处：《物理》2010年第10期674-681,共8页Physics

基　　金：国家自然科学基金(批准号:19674001)资助项目

摘　　要：掺杂锰氧化物属于强关联材料,实验上明确显示出强电-声子耦合对于材料性质(如输运性质和铁磁性质)的影响.极化子是对氧化物材料中载流子行为的近似描述.顺磁状态的掺杂锰氧化物样品电阻率随温度变化关系可以用极化子理论进行很好的描述,并且数据分析还提供了与材料性质有关的微观参数.利用文章作者提出的跃迁极化子交换相互作用与材料铁磁有序温度TC联系的关系式,对掺杂锰氧化物样品磁场下的测量结果进行了数据拟合.非常好的拟合结果说明,跃迁极化子决定交换耦合及铁磁有序的物理图像和数据拟合中使用的近似是合理的.在数据拟合基础上对掺杂锰氧化物和巨磁电阻(CMR)效应的物理图像进行了讨论.Doped manganites belong to strongly correlated materials that demonstrate the strong influence of electron-phonon coupling on properties such as transport and magnetism. The transport properties of oxide materials can be described by the polaron model, and for epitaxial doped manganite films in the paramagnetic state, by the small polaron hopping model that also provides parameters such as the thermal hopping energy for carriers. By using a formula that we derived for the relationship between the ferromagnetic ordering temperature and exchange coupling caused by hopping polarons, a simulation was performed with the experimental data of epitaxial doped manganite films in applied magnetic fields. The good agreement between the experimental data and energy balance expression indicates that the simulation is reasonable. Based on these results, the colossal magnetoresistanee effect for doped manganites is discussed.

关 键 词：掺杂锰氧化物 极化子 铁磁有序 巨磁电阻效应 

分 类 号：O482.523[理学—固体物理]