应力对钙钛矿型过渡金属氧化物铁电、铁磁性质影响的研究

As the thin-film deposition methods, such as molecule beam epitaxy, pulsed laser deposition, and metal organic chemical vapor deposition, become mature technologies, exploring the novel functions of heterostructure and superlattice structures with similar crystal structures but different physical properties has attracted a great attention. By choosing crystals with different lattice mismatch and atomic compositions, anisotropic strain not only can manipulate the material properties of constituents, but also can create novel properties its constituents haven't. In this project, the first-principles method is used to study: (1) the impact of epitaxial strain on the reconstruction of interface structure and electronic structure. How these reconstruction processes mediate the coupling among constituent materials and affect the ferroelectric, ferromagnetic, and magnetoelectric properties of heterostructures and superlattice structures?(2) the effect of shear strain on the asymmetrical properties of double well potential of ferroelectrics and magnetocrystalline anisotropy energy of ferromagnets. How the curvature induced polarization and magnetization reversal of ferroelectrics and ferromagnet can be used for possible device purpose

随着分子束外延、激光脉冲沉积和金属有机化学气相沉积等薄膜生长技术的日益成熟，研究具有结构类似但是物性互补的钙钛矿氧化物异质结和超晶格结构的新颖物性成为近年来的热门课题。通过选择不同的晶格失配和原子组分，各向异性应变不仅可以调控单一材料的铁电铁磁性质，更可以制备出单一材料所不具备的复合多铁物性。本项目采用第一性原理研究异质结材料和超晶格材料中外延应力导致的界面电子结构重整和切应力导致的中心反演对称破缺对材料电磁性质的调控。重点研究外延应力对铁电铁磁性质和磁电耦合性质的调控机制和切向应力对电极化的双势垒和磁晶各向异性能非对称性的影响。探讨多铁材料的优化设计和薄膜曲率与单向极化关系可能的器件应用。

随着分子束外延和金属有机化学气相沉积等薄膜生长技术的日益成熟，研究具有结构类似但是物性互补的钙钛矿氧化物异质结和超晶格结构的新颖物性成为近年来的热门课题。通过选择不同的晶格失配和原子组分，各向异性应变不仅可以调控单一材料的铁电铁磁性质，更可以制备出单一材料所不具备的复合多铁物性。本项目采用第一性原理研究原子掺杂的内禀化学内应力，异质结材料和超晶格材料的外延应力导致的体和界面电子结构重整，内禀应力和切应力导致的中心反演对称破缺对材料电磁性质的调控。重点研究了元素掺杂的化学内禀应力如何将反铁磁铁电体转化为亚铁磁铁电体，铁电铁磁超晶格如何集成和改善多铁性质，外延应力对磁电耦合性质的调控以及如何应用切向应力梯度带来的电极化双势垒和磁晶各向异性能的非对称实现力学电畴的写入等进行了深入的探讨。取得了项目所期望的一系列结果。