Ru掺杂锰氧化物磁性及电输运行为的研究

发布时间：2018-05-18 15:05

本文选题：锰氧化物 + 电子相分离　；参考：《南京大学》2015年硕士论文

【摘要】：锰氧化物具有诸多奇特的物理性质,比如磁电阻效应、电致电阻效应、同位素效应以及多铁性等,引起了人们广泛的关注和研究。锰氧化物体系中发现存在电子相分离现象,而电子相分离的产生涉及锰氧化物中多个电子相共存,包括铁磁金属相和反铁磁电荷有序相,这主要是由于锰氧化物中电荷、轨道、自旋以及晶格畸变等多种自由度的相互耦合引起的。锰氧化物中Mn位微量的离子或电子掺杂,都会使体系的电子相改变。研究发现,锰氧化物中用微量Ru进行Mn位掺杂时,有效地促进了体系中铁磁金属相的形成,居里温度也相应的提高,这与掺杂其他离子(比如Cr、Fe、Al等)是不同的,因此锰氧化物中Ru的Mn位掺杂引起了关注。之前的研究发现,锰氧化物中的Ru掺杂主要是Ru4+和Ru5+离子,而居里温度的提高是由于体系中Mn3+-Ru4+(Ru5+)铁磁的超交换相互作用引起的。然而有关Mn-O-Ru之间的相互作用以及其对体系电子相分离的影响仍然存在争议,目前还没有定论。锰氧化物由于Ru掺杂而导致体系出现反常金属-绝缘体转变的原因也是不清楚的。在本论文中,我们研究了不同Ru掺杂浓度LPCMRO的磁性和电输运性能,并进行了细致而又深入的探讨。全文的主要内容安排如下：第一章,简述锰氧化物的研究历史以及主要的物理性质。然后对电致电阻效应做了简要的介绍。第二章,简述样品的制备方法以及表征手段,并简要介绍了PLD实验室对样品进行物性表征的实验仪器及其原理。第三章,我们采用传统的固相反应法制备了不同Ru掺杂浓度的LPCMRO样品,研究了其磁性和电输运性质,发现了很多有趣的现象：比如样品磁性和电阻率随温度变化的关系,还有外电场的变化会使样品的电阻率发生明显的改变,而外磁场又会抑制这种反常电致电阻效应等。我们对这些有趣的物理现象进行了讨论与分析。第四章,全文的总结与展望。
[Abstract]:Manganese oxides have many peculiar physical properties, such as magnetoresistive effect, electroresistance effect, isotope effect and polyferric property. The phenomenon of electron phase separation is found in manganese oxide system, and the generation of electronic phase separation involves the coexistence of many electronic phases in manganese oxide, including ferromagnetic metal phase and antiferromagnetic charge ordered phase, which is mainly due to the charge and orbit in manganese oxide. The coupling of various degrees of freedom, such as spin and lattice distortion, is caused. The trace amount of mn ion or electron doping in manganese oxide can change the electronic phase of the system. It is found that the formation of ferromagnetic metallic phase in the system is effectively promoted when mn site is doped with trace Ru in manganese oxide, and the Curie temperature is also increased accordingly, which is different from doping other ions (such as Cr-Fe, Al, etc.). Therefore, mn doping of Ru in manganese oxide has attracted much attention. It has been found that the doping of Ru in manganese oxides is mainly due to the Ru4 and Ru5 ions, and the increase of Curie temperature is due to the superexchange interaction of Mn3 -Ru4 and Ru5) ferromagnetic in the system. However, the interaction between Mn-O-Ru and its influence on the electronic phase separation is still controversial. The reason of abnormal metal-insulator transition due to Ru doping is also unclear. In this thesis, we studied the magnetic and electrical transport properties of LPCMRO with different Ru doping concentrations, and made a detailed and in-depth study. The main contents of this paper are as follows: chapter 1, briefly describes the history and physical properties of manganese oxides. Then the electric resistance effect is briefly introduced. In the second chapter, the preparation methods and characterization methods of the samples are briefly described, and the experimental instruments and their principles for the physical properties of the samples in PLD laboratory are briefly introduced. In chapter 3, we have prepared LPCMRO samples with different Ru doping concentration by traditional solid state reaction method. We have studied their magnetic and electrical transport properties, and found many interesting phenomena, such as the relationship between sample magnetism and resistivity with temperature. The change of the external electric field will make the resistivity of the sample change obviously, but the external magnetic field will restrain the anomalous electroresistance effect and so on. We have discussed and analyzed these interesting physical phenomena. Chapter IV, the full text of the summary and prospects.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ137.12

【相似文献】