极性金属是一类极性与金属性可以共存的材料，非常稀有，这是由于金属性材料中的导电电子会完全屏蔽静电偶极矩，从而破坏极性的形成。目前，阐明极性与金属性为何共存的微观物理机制是该研究方向的核心科学问题之一。为了解决上述问题，基于界面调控，本项目提出了具有金属-绝缘相变特性的新型极性金属材料的设计思路。申请人拟利用脉冲激光沉积技术制备出高质量的新型极性金属薄膜，并通过衬底应变工程来调控薄膜的金属-绝缘相变行为，利用同步辐射共振X射线吸收谱技术揭示薄膜中极性绝缘态到极性金属态的电子结构演化规律，揭示极性与金属性共存的微观物理机理。本项目的实施将为实现多铁性金属和设计新型磁电耦合器件奠定基础。

Polar metals, commonly defined by the coexistence of polar crystal structure and metallicity, are thought to be scarce because the electrostatic dipole moments favoring the polar structure are expected to be fully screened by the conduction electrons of a metal. At present, one of the fundamentally important questions of exploring polar metals is understanding the coexistence of polar crystal structure and metallicity. To address the issue, based on interface engineering, we propose a design of new polar metals with the metal-insulator transition. High-quality films will be synthesized by the laser molecular beam epitaxy (laser-MBE) in a layer-by-layer method. Strain engineering will be applied to tune the behavior of the metal-insulator transition. To uncover the mechanism of coexisting polarity and metallicity, we will carry out synchrotron-based resonant x-ray absorption spectroscopies to investigate the evolution of the electronic structure of polar metal-insulator transition. Our project provides a new path to develop multiferroic metals and to design new magnetoelectric devices.