Epitaxy, electrical transport and phase transitions in charge ordered Ruddlesden-Popper perovskite oxide layers

电荷有序 Ruddlesden-Popper 钙钛矿氧化物层的外延、电传输和相变

• 批准号: 452483478
• 负责人: Professor Dr. Christian Jooss
• 金额: --
• 依托单位: Institut für Materialphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/452483478?language=en
• 关键词: Epitaxy; electrical; transport; phase; transitions

In this project we want to investigate growth mechanisms and structure-property relationships of semi-doped epitaxial Pr-Ca-Mn-O (PCMO) Ruddlesden-Popper (RP) films of order n=1 and n=2. The RP phases of the manganates represent quasi two-dimensional highly correlated electron systems with polaron quasi-particles, which can crystallize to a charge-ordered phase. The charge order can be "melted" by external stimuli and has long-lived electron-hole-pair excitations. This enables fascinating new functions, especially in photovoltaics, sensor technology and microelectronics. The main goal of the project is to gain an understanding of the mechanisms that determine the growth orientation of epitaxial layers. These are not only determined by the mismatch to the substrate, but also by the chemistry of the surface / interface. Furthermore, the defects resulting from stress relaxation will be determined and their effect on the ordering temperature will be investigated. The synthesis as thin films offers the possibility to control the properties of the films by epitaxy, strain and defects in order to influence the functionalities in heterojunctions. The deposition is performed by pulsed laser deposition (PLD). The main focus of the characterization is the investigation of epitaxy and strains (X-ray diffraction, TEM), the growth process (AFM, SEM) and elastic stresses (beam bending method). This is done in combination with temperature dependent electrical transport measurements in magnetic and electric fields. The investigation of defects and charge order is performed by means of high-resolution transmission electron microscopy (HRTEM). Based on the first phase of the project, which is focused on Ruddlesden-Popper-Manganate films of order n=1 with a Tc=320 K, the second phase will be extended to the order n=2 and higher, which have higher transition temperatures of up to 370 K.

在这个项目中，我们希望研究半掺杂的外观外观pr-ca-mn-o（PCMO）ruddlesden-popper（RP）膜N = 1和n = 2的生长机制和结构性质关系。锰酸盐的RP阶段代表了与极性颗粒的准二维高度相关的电子系统，该电子系统可以结晶为电荷订购相。电荷顺序可以被外部刺激“融化”，并具有长寿命的电子孔对激发。这可以使引人入胜的新功能，尤其是在光伏技术，传感器技术和微电子方面。该项目的主要目的是了解确定外延层增长取向的机制。这些不仅取决于与底物的不匹配，而且还取决于表面 /界面的化学。此外，将确定应力松弛导致的缺陷，并研究其对订购温度的影响。作为薄膜的合成提供了通过外观，应变和缺陷来控制薄膜特性的可能性，以影响异质界的功能。沉积通过脉冲激光沉积（PLD）进行。表征的主要重点是对外延和菌株（X射线衍射，TEM），生长过程（AFM，SEM）和弹性应力的研究（光束弯曲方法）。这与磁场和电场中的温度依赖性电运输测量结合在一起。缺陷和电荷顺序的研究是通过高分辨率透射电子显微镜（HRTEM）进行的。基于该项目的第一阶段，该项目的重点是ruddlesden-Popper-Manganate n = 1的ruddlesden-popper-manganate膜，TC = 320 K，第二阶段将扩展到n = 2及更高阶，其过渡温度较高，最高为370 k。