EuTiO3:MgO垂直有序结构中的负压力构建及多铁性调控研究

压力作为钙钛矿薄膜晶格畸变和能带重构的有效方式，已在多铁性研究和光电子器件中被广泛应用。其中正压力（界面二维应变）因其较窄的应变范围已成物性调控难以突破的瓶颈，因此改变压力作用方式成为了该领域的前沿问题。负压力则是通过晶格三维膨胀引发材料内部离子偏移和键角改变以实现物性调控，理论上具有更宽的压力范围和更强的物性调控效果。本项目计划在PMN-PT衬底上制备具有垂直有序结构的EuTiO3:MgO(ETO:MgO)复合薄膜，利用PMN-PT的水平电致伸缩与垂直界面的晶格失配，为单相ETO材料提供连续可调的负压力。系统地研究此体系中垂直结构演化、负压力形成机理和铁磁-铁电性质调控等基本问题。在此基础上，分别从宏观和微观的角度构建负压力调控ETO相自旋-晶格耦合的物理模型。本项目不仅能为揭示垂直结构中负压力对多铁性质的调控机理提供实验和理论依据，而且可为材料物性优化及器件性能升级提供新的技术手段。

Pressure shows a significant application on multiferroics and optoelectronics due to its tuning effect on the crystal distortion and electronic reconstruction of the perovskite films. However, the narrower range of the positive pressure (lateral strain) leads to the restriction on the modification of the properties. Recently, how to change the way of the pressure has become the frontier in this field. In contrast, the negative pressure (NP) can enable the lattice expansion in three mutually perpendicular directions, obtaining the purpose of enhancing the pressure intensity and the properties of the material by the alteration of the ion displacement and the bond angle..This project aims to fabricate the vertical-aligned EuTiO3:MgO (ETO:MgO) nanocomposite thin films, and combine the electrostrictive in PMN-PT substrate and the lattice mismatch in vertical interface to generate the continuously adjustable NP. Then, we plan to systemically study the fundamental problems of vertical structure evolution, NP formation mechanism and multiferroic modification. Furthermore, the physical model of negative-pressure-manipulated spin-lattice coupling in the ETO can be better explored in the view of macroscopy and microscopy. The project not only lays a foundation to deepen the understanding of the coupling mechanism between the NP and multiferroic in the vertical-aligned structure, but also demonstrates that NP as a controlling effect can be a new path to enhance the functionality of materials and upgrade the usage of devices.