第II类多铁性体薄膜与异质结的制备及物性研究

The type-II multiferroics as novel class of strongly correlated electron systems have been receiving special attentions due to the underlying physics associated with the multiferroic order coupling and inter-manupulations, which is important for message storage and energy conversion. Study on the type-II multiferroic thin films and heterostructures is an essential part of multiferroic research, and can significantly enrich the multiferroic physics, also improve the potential application. Motivated by earlier works including our own contributions on the synthesis and characterizations of type-II multiferroic compounds and multiferroic thin films and heterstructures, this proposal is intended to address several major issues of the physics and multiferroic order coupling in typical type-II multiferroic thin films and heterostructures, including: (1) Multiferroic modulation and physics of thin films with spiral-spin-ordering; (2) Mechanism and multiferroicity of E-type antiferromagnetic thin films; (3) Novel physical effects, e.g., exchange bias and possible multiferroicity enhancement induced by the coexistence and competition between differnet multiferroic mechanisms, in type-II multiferroic heterostructures.Current project should be performed mainly from the experimental aspects, while some related theoretical calculations will also be carried out, and the target is to reveal novel physical properties and deeply understand the associated physics of multiferroic thin films and heterostructures.

第II类多铁性体蕴含深刻的铁性序耦合与调控物理，是关联电子物理关注的热点方向之一，也对信息存储及能量转换等应用领域的发展具有重要意义。开展相关薄膜与异质结研究工作是第II类多铁性体发展十年来的一个必然趋势，也是丰富多铁性物理，并推动应用的关键所在。本申请以申请人近年来在第II类多铁性物理及多铁性异质结方面的研究工作为基础，着重开展对第II类多铁性薄膜中多铁性调控及异质结中新物理效应的创新研究，深刻理解其中的物理机制。主要包括：(1)螺旋自旋多铁性体薄膜中多铁性调控及相关物理问题；(2)E 型反铁磁多铁性体薄膜中多铁效应及机制(3)第II类多铁性体异质结中的交换偏置效应及多种多铁性机制共存竞争诱导多铁性增强效应。本项目以实验探索为主，结合理论，揭示新的多铁效应与物理。

在项目执行的四年中，项目负责人和其团队成员根据申请书既定的研究计划，重点开展了多铁性锰氧化物薄膜与异质结的研究。深入研究了衬底应力，畴结构，多重自旋关联等效应对薄膜中多铁性与磁电效应的调控与机理，取得了一系列的研究成果，较好实现了既定的科学目标。具体研究成果包括: i) 系统研究了RMnO3（R为稀土离子）薄膜中多铁性类孪晶畴对物理性能的调控；ii）揭示了RMnO3薄膜中多重自旋关联对多铁性的影响；iii）实现薄膜应力对RMnO3薄膜中多铁性能的调控；此外，在本项目的支持下，我们拓展研究内容至强自旋轨道耦合体系5d氧化物Sr2IrO4中，深入研究了其中与强自旋轨道耦合相关的电、磁物性关联，取得了较好的结果。