过渡金属氧化物表/界面磁性及其调控

由于对称破缺，表界面常表现出独特的物理行为。过渡金属氧化物的多自由度、多竞争机制为表面效应注入了新物理内涵。以往锰氧化物工作多围绕磁电子输运及光电行为展开，由于缺少磁敏感量有效描述表界面磁状态，很少涉及表界面磁性，特别是反铁磁体系表面磁性。而过渡金属氧化物表界面磁性无论对基础科学还是对应用科学而言都具研究价值。以交换偏置及磁邻近效应分析为基础，本课题将围绕表界面磁性展开，重点关注：典型铁磁、反铁磁氧化物表面行为与体行为间的异同及关联，磁相变、磁畴结构重整以及热涨落对表界面磁性的影响，特别关注自旋结构共线-非共线磁相变及不同磁结构类型间相变的影响。通过表界面极性、层间磁关联调控探索表界面磁性改性的途径。研究目标是阐明表界面磁性和体磁性间异同及关联，揭示界面电荷转移、轨道择优取向对表界面磁性的影响规律，探索表界面磁性调控的有效途径，进而为氧化物人工结构材料、器件的设计铺平

Due to symmetry breaking, surface/interface usually owns unique physical properties. The coexistence of more than one degrees of freedom and more than one competitive mechanisms in transition metal oxides assigns abundant physical complications to surface/interface effects. However, most of the previous works for manganites,the typical magnetic oxides, focused on magneto-resistive properties, and the surface/interface magnetism was less considered for lacking of appropriate analysis techniques, despite its importance for both fundmental and applied researches. Based on the analyses of exchange bias and magnetic proximate effects, in the present project we will perform a comprehensive study on surface/interface magnetism. The mains concerns are similarities and differences of bulk and surface/interface magnetism for both ferromagnetic and anti-ferromagnetic manganites and other relevant oxides. Particular attention will be paid to the effects of magnetic transition, including collinear to non-collinear spin structure transition, on surface magnetism. It will be tried to manipulate surface/interface magnetism by interface engineering based on well controlled epitaxial growth technique. Through these works,we hope to find the key factors affecting surface/interface magnetism, address the similarities and differences of bulk and surface/interface magnetism and their correlation, find feasible approaches towards surface/interface magnetism engineering which may pave the way towards the design of novel oxide-based artificial materials/devices.