三方四方相共存多铁性薄膜全电场调控的磁交换偏置效应研究

提出制备全电场调控的以三方相/四方相共存掺杂BiFeO3铁磁层、三方相BiFeO3反铁磁层并具有磁交换偏置效应同质双层膜的新思想。研究掺杂应力诱导铁磁相的形成机理、电场诱导的铁电应力对铁磁相与反铁磁相界面磁交换偏置效应调控规律及其机理。具体地，通过外加电场调控三方相BiFeO3中铁电畴取向并通过磁电耦合来调控BiFeO3铁磁畴取向和形态来实现对掺杂BiFeO3铁磁性薄膜表面的局域磁矩进行调控，进而实现电场对铁磁层与反铁磁层之间磁交换偏置耦合效应调控。提出宏观磁交换偏置效应测量与准同型性相界处局域磁畴和铁电畴及其磁电耦合受电场应力调控进行静态和动态的多方法和多测度的同步协同测量新技术和新方法。研究应力导致的Fe-O八面体旋转取向对同质双层膜中磁电耦合机理、磁交换偏置场、铁磁层磁矫顽力和training效应的调控规律及其机理。为设计和制备出具有应用价值的磁电耦合随机存储器件提供理论和技术支持。

In this proposal, a novel full electrical field controlled magnetic exchange bias bilayer is suggested. This new kind of magnetic exchange bias bilayer is fabricated by doped BiFeO3(BFO) ferromagnetic (FM) film with co-exiting R3c and orthorhombic phases and antiferromagnetic (AFM) R3c BFO film. Researches are focused upon the mechanism of the ferromagnetism induced by the doped resulted chemical strains, as well as the mechanism of the external electrical field controlled exchange bias between the doped BiFeO3 FM layer and the AFM BiFeO3 layer. In detail, the polarization of the magnetic domains in BFO is controlled by external electric filed due to ME effect, thus, the FM or AFM coupling between doped BFO and BFO can be established and modulated by electric field. In this way, a novel full electric filed controlled exchange bias effect in BFO related homosturcture bilayer can be realized. We propose study the electric field controlled globe properties of the exchange bias effects and the local magnetic-, ferroelectric- domains, as well as the ME effects in the morophotropic phase boundary between the doped BOF and BOF homo-structure bilayer, including static and dynamic in multi-scale and multi-technologies integrated and cooperated. Based upon these studies, we will reveal the mechanism of the stain, due to the rotation of Fe-O octahedral structure in doped BFO and BFO, induced modulation of the full electric field controlled magnetic exchange bias, including exchange bias field, magnetic coercivity, training effects. The conclusion of the study will supply information for the design and fabrication of the magnetoelectric random access memories devices both in theoretical and technological.