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Raman spectroscopic investigations of epitaxial multiferroic thin films

外延多铁性薄膜的拉曼光谱研究

基本信息

批准号：
186107688
负责人：
Dr. Cameliu Himcinschi
金额：
--
依托单位：
Institut für Theoretische Physik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2014-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/186107688?language=en
关键词：
Raman spectroscopic investigations epitaxial multiferroic

项目摘要

In multiferroic, ferroelectric, and ferromagnetic materials the lattice dynamics, which determine the fundamental ferroic properties, can be influenced in a controlled way by strain engineering. In this project a systematic study of the strain influence on the optical phonons in epitaxial films (such as BiFeO3 and CoFe2O4) will be performed by Raman spectroscopy. To this purpose, the strain will be induced by a piezoelectric substrate (such as PMN-PT). This method allows to distinguish the effect induced by strain from overlapping extrinsic effects (caused by growth conditions or different substrate quality) that usually occur when the strain engineering is performed by growing the desired films on substrates with different lattice parameters. Another focus of this project lies in the Raman spectroscopic investigation of ferroelectric/magnetic heterostructures. Ferroelectric / magnetic composite systems (as for example BiFeO3 / CoFe2O4) have multiferroic properties at room temperature, due to the large polarization and magnetization of the component materials. We will investigate the magnetoelastic coupling in such system by employing magnetic-field-dependent Raman spectroscopy. Specifically, we will compare the magnetostriction influence on the Raman-active phonons for BiFeO3 / CoFe2O4 bi-layers and self-assembled (pillar/matrix) BiFeO3 / CoFe2O4 systems to assess the effect of the size of the nanostructures on the magnetoelastic coupling.

在多铁性、铁电性和铁磁性材料中，决定基本铁性的晶格动力学可以受到应变工程的控制。在本项目中，将利用拉曼光谱系统地研究应变对外延薄膜(如BiFeO_3和CoFe_2O_4)中光学声子的影响。为此，应变将由压电衬底(如PMN-PT)诱导。这种方法允许区分应变引起的效应和重叠的外在效应(由生长条件或不同的基片质量引起)，当通过在具有不同晶格参数的基片上生长所需的薄膜来执行应变工程时，通常会出现重叠的外在效应。本项目的另一个重点是铁电/磁性异质结构的拉曼光谱研究。铁电/磁复合体系(如BiFeO_3/CoFe_2O_4)由于组成材料的大的极化和磁化强度，在室温下具有多铁性。我们将利用依赖于磁场的拉曼光谱来研究这种系统中的磁弹性耦合。具体地说，我们将比较BiFeO_3/CoFe_2O_4双层和自组装(柱状/基质)BiFeO_3/CoFe_2O_4体系的磁致伸缩对拉曼活性声子的影响，以评估纳米结构的尺寸对磁弹性耦合的影响。