Investigating thermoelectricity in maerials with different strength of electronic correlations

研究具有不同电子关联强度的材料的热电性

• 批准号: 120485794
• 负责人: Professor Dr. Hanns-Ulrich Habermeier
• 金额: --
• 依托单位: Max-Planck-Institut für Festkörperforschung (MPI-FKF)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/120485794?language=en
• 关键词: Investigating; thermoelectricity; maerials; different; strength

The nanostructuring of weakly-to-moderately correlated thermoelectric materials has proven in recent years to largely enhance the respective figure of merit. Thus the key focus in the second funding period of the present project is to investigate the same structering issue in the context of strongly correlated materials, namely selected transition-metal oxides such as cobaltates, manganites, ferrates, etc. . We will study, both theoretically as well as experimentally, thin-films and heterostructures as well as on the experimental side even more complicated morphologies. Especially the influence of a given surface will be examined in theoretical detail, since the phenomena elucidated there may apply to various geometries. Studying heterostructures and multi-layers will allow for the description of emergent transport properties when bringing different materials systems in direct contact. Further advanced superlattice geometries for the given materials will challenge the band-theory concept in the presence of strong electronic correlations. The theoretical modeling will benefit from recent development within the framework of LDA+DMFT in combination with a transport approach building up un the generic Kubo formalism. This allows to go beyond the constant-relaxation time approximation for the Boltzmannequation approach and can deal with e.g. the realistic temperature effects, i. e. the correct description of the flow of electronic entropy. Contact will be made with thermal transport measurements within other projects in the main project.Furthermore the effect of spin-orbit coupling on the thermoelectricity of higher 4d/5d transition-metal oxides will be an additional point of interest in our research effort. The important competition between the complexity enhancement of the band structure and the increased quenching of spin fluctuations in the presence of the spin-orbit interaction deserves deeper studies in order to possibly open the the door for thermoelectricity research in the regime of heavier elements aside from the well-known weakly correlates systems, such as e.g. Bi2Te3.

近年来，弱相关热电材料的纳米结构已被证明可以大大提高各自的品质因数。因此，本项目第二个资助期的重点是在强相关材料（即选定的过渡金属氧化物，如钴酸盐、亚锰酸盐、高铁酸盐等）的背景下研究相同的结构问题。我们将从理论上和实验上研究薄膜和异质结构，以及在实验方面甚至更复杂的形态。特别是，将在理论上详细研究给定表面的影响，因为其中阐明的现象可能适用于各种几何形状。研究异质结构和多层将有助于描述不同材料系统直接接触时出现的传输特性。给定材料的进一步先进的超晶格几何形状将在存在强电子相关性的情况下挑战能带理论概念。理论建模将受益于 LDA+DMFT 框架内的最新发展，并结合在通用 Kubo 形式主义中建立的传输方法。这允许超越玻尔兹曼方程方法的恒定松弛时间近似，并且可以处理例如真实的温度效应，i。 e.电子熵流的正确描述将与主项目中其他项目中的热传输测量进行联系。此外，自旋轨道耦合对更高 4d/5d 过渡金属氧化物热电的影响将是我们研究工作的另一个兴趣点。在自旋轨道相互作用存在的情况下，能带结构的复杂性增强和自旋涨落的增强淬灭之间的重要竞争值得更深入的研究，以便可能为除了众所周知的弱相关系统之外的较重元素领域的热电研究打开大门。 Bi2Te3。