纳米复合壳层结构颗粒体系的磁场可控制备及偏置效应调控机制研究

Recently, stable and controllable exchange bias effect has become a principal method to solve the problem of miniaturization of nano-devices for magnetic storage, which has been a hot subject in fundamental and applied research of magnetism. In this project, we will select several types of composite core-shell structures with different shape anisotropy as research object, such as Antiferromagnetic/Ferromagnetic or Paramagnetic/Ferromagnetic, etc. With induction of magnetic field or electric field in the growth process, we can control the shape of crystals, geometric dimension, micro-structure, and roughness of interface. Using a variety of experimental methods and characterizations, we can further systematically research the impacts on exchange bias effect such as material nuclear shell morphology, crystalline structure, magnetic anisotropy, interfacial microcosmic structure and magnetic exchange bias effect. We will also adopt the Monte Carlo method to analyze the effects of the overall shape, size, and the interface coupling strength of nanoparticles on the magnetic properties of several typical nanostructures (such as sphere and cube). Finally, we will clarify the microscopic mechanisms of magnetic bias effect combined with the experimental and theoretical results. The work is expected to provide an important guideline for controllable design and preparation of core-shell structures of magnetic nano-materials with excellent performance.

稳定、可控的偏置效应是解决当今小型化微纳磁存储器中超顺磁瓶颈问题的主要方案，为磁电子学基础研究和实际应用的热点研究课题之一。本课题选取形状各向异性的多种反铁磁-铁磁、顺磁-铁磁等核壳结构样品为研究对象，在材料晶体生长中加入磁场或电场诱导来实现对晶体的形状、几何尺寸及界面的微结构、粗糙度的可控制备，结合多种表征手段，研究材料核壳层的形貌、晶体结构、磁各向异性、界面微观结构对核壳样品的偏置效应大小和稳定性等磁性参量的影响。在理论上，采用蒙特卡罗微磁学理论，从纳米颗粒的整体形状、大小和界面耦合强度的重要因素出发，探讨几种特定典型的纳米结构（如球形和立方体等）磁性能。综合实验和理论结果，揭示核壳纳米颗粒体系中磁偏置性能的微观机制，为优良性能的壳层磁纳米材料的设计、制备提供实验和科学理论基础。

稳定、可控的偏置效应是解决当今小型化微纳磁存储器中超顺磁瓶颈问题的主要措施。我们选取了形状各向异性的多种反铁磁-铁磁、顺磁-铁磁等核壳结构样品，在材料晶体生长中加入了磁场诱导来实现对晶体的形状、几何尺寸等参数的可控制备，结合多种表征手段，研究了材料核壳层的形貌、晶体结构、磁各向异性、界面微观结构对LSMO等样品的偏置效应大小和稳定性等磁性参量的影响。.在理论上，我们采用了磁学理论，从纳米颗粒的整体形状、大小和界面耦合强度的重要因素出发，探讨球形、立方体磁性能。我们在综合实验和理论结果基础上，揭示了核壳纳米颗粒体系中磁偏置性能的微观机制，制备了良好性能的壳层磁纳米材料。