3D tailoring of all-oxide heterostructures by ion beams

在多功能氧化物材料中，电荷、自旋、轨道和晶格参数之间的相互关系在很大程度上得到了证实，这些材料表现出各种奇异的性质，包括超导性、绝缘体-金属转变、巨磁阻、电荷有序和轨道有序等。特别是，通过温度、压力或化学控制，可能导致这些系统中的奇异现象。然而，事实证明很难对这种互动进行精细调整。在这种情况下，通过离子辐照的缺陷工程，这可以引入应变和电子无序，已经成为一个强大的技术来微调难以接近的复杂相的氧化物薄膜。在这个提议中，我们的目标是调制的磁性，电性和铁性的NiCo 2 O 4和BiFeO 3的异质结构通过离子辐照。通过采用光刻和/或聚焦离子束，可以实现3D缺陷工程，从而定制NiCo 2 O 4/BiFeO 3的物理性质。最终的目标是检验这种调谐异质结构作为新型自旋电子学器件的场所。国立交通大学的研究小组精通于外延NiCo 2 O 4和BiFeO 3薄膜的制备。HZDR的小组有可能根据需要用不同样品和能量的离子辐照这些薄膜。详细的结构，磁性和电气特性将在HZDR使用的技术进行。切姆尼茨工业大学的研究小组将使用密度泛函理论（DFT）的自旋极化电子结构计算来理解这些变化。因此，来自这些小组的科学家的组合可以建立一种新的氧化物异质结构的3D定制途径，用于设计新的功能。

Inter-relations among charge, spin, orbital and lattice parameters are largely demonstrated in multi-functional oxide materials which exhibit a variety of exotic properties, ranging from superconductivity, insulator-metal transition, colossal magnetoresistance, charge ordering, and orbital ordering, etc. In particular, tilting a delicate energy balance in lattice interactions and kinetics, achieved by temperature, pressure or chemical control, may result in exotic phenomena in these systems. However, fine-tailoring such interactions has proven difficult. In this context, defect engineering by ion irradiation, which can introduce strain and electronic disorder, has emerged as a powerful technique to fine tune inaccessible complex phases of oxide thin films. In this proposal, we aim at the modulation of the magnetic, electrical and ferroic properties of NiCo2O4 and its heterostructure with BiFeO3 by ion irradiation. By employing lithography and/or focused ion beam, 3D defect engineering therefore tailoring physical properties of NiCo2O4/BiFeO3 can be realized. The final goal is to exam such a tuned heterostructure as a venue of novel spintronics devices. The National Chiao Tung University group is well versed in the fabrication of the epitaxial NiCo2O4 and BiFeO3 thin films. The group at HZDR has the possibility of irradiating these films with ions of different specimen and energies on demand. The detailed structural, magnetic and electric characterization will be performed using the techniques at HZDR. The group at TU Chemnitz will use spin-polarized electronic structure calculations with density functional theory (DFT) in understanding the changes. Therefore, the combination of scientists from these groups can establish a new pathway of 3D tailoring of oxide heterostructures useful for designing new functionalities.