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，我们想要研究 n=1 和 n=2 阶半掺杂外延 Pr-Ca-Mn-O (PCMO) Ruddlesden-Popper (RP) 薄膜的生长机制和结构-性能关系。锰酸盐的RP相代表具有极化子准粒子的准二维高度相关电子系统，其可以结晶成电荷有序相。电荷顺序可以被外部刺激“熔化”，并且具有长寿命的电子空穴对激发。这使得令人着迷的新功能成为可能，特别是在光伏、传感器技术和微电子领域。该项目的主要目标是了解决定外延层生长方向的机制。这些不仅取决于与基材的不匹配，还取决于表面/界面的化学性质。此外，还将确定由应力松弛引起的缺陷，并研究它们对有序温度的影响。薄膜的合成提供了通过外延、应变和缺陷控制薄膜特性的可能性，以影响异质结的功能。沉积通过脉冲激光沉积（PLD）进行。表征的主要重点是外延和应变（X 射线衍射、TEM）、生长过程（AFM、SEM）和弹性应力（梁弯曲法）的研究。这是结合磁场和电场中与温度相关的电传输测量来完成的。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。基于该项目第一阶段的重点是 n=1 阶、Tc=320 K 的 Ruddlesden-Popper-Manganate 薄膜，第二阶段将扩展到 n=2 阶及更高阶，具有更高的转变温度高达 370 K。