本計畫旨在研究薄膜及複合結構型態下之鐵磁性氧化物材料系統，包括SrRuO3、 Nd0.5Ca0.5.xSrxMnO3 等。我們將深入探討該類材料之鍍膜技術、材料之間以及材料與基板間的相容性，並擴及相關的磁傳輸特性等。近年來研究人員對於強關聯氧化物材料系統之興趣持續加溫，尤其是perovskite結構之氧化物，原因是它們在磁電傳輸特性上所呈現的豐富相貌。各種鍍膜技術的快速進展更使此類材料的新特性達到前所未有的境地。本計畫擬針對兩種強關聯材料系統 (SrRuO3 與Nd0.5Ca0.5.xSrxMnO3)，探索其在薄膜及複合結構型態下的行為。研究發現SrRuO3 薄膜呈現許多有趣的自旋偏振行為。其化學結構穩定同時可與氧化鋁 (Al2O3) 形成良好介面，因此在自旋相關的元件應用方面引起矚目。另一方面，在先前的研究工作中，我們發現Nd0.5Ca0.5.xSrxMnO3 系統具有多樣的磁相變以及電荷序化 (charge-ordering) 等特性。本專題計畫具有三重目標：(一) 嘗試以不同的鍍膜技術將上述材料製作成薄膜，並且有系統地研究其磁傳輸特性；(二) 製作以鐵磁性金屬、普通金屬及鐵磁性氧化物等不同材料組合而成之複合結構。我們將利用平行電流以及垂直電流等磁阻測量方式研究 (鐵磁性金屬/ 鐵磁性氧化物)、(鐵磁性氧化物/ 鐵磁性氧化物) 之間的長程耦合效應；(三) 研究鐵磁性氧化物與金屬接觸介面的結構與磁性特質，並深入剖析其對於複合結構傳輸行為的影響。
This project is determined to study the ferromagnetic oxide systems, including SrRuO3 and Nd0.5Ca0.5.xSrxMnO3, in the form of thin-films and hetero-structures. Details of their deposition techniques, their compatibility with each other and the substrate materials, and the correlated magneto-transport properties will be investigated. There has been an increasing interest in the physics of strongly correlated oxide materials in recent years, and especially the perovskite-based oxides because they exhibit a wide variety of electromagneto-transport properties. The fast development of thin film deposition techniques also helps to exploit the properties of these materials previously unobtainable. In this project we propose the study of two strongly correlated material systems, i.e. SrRuO3 and Nd0.5Ca0.5.xSrxMnO3, in the form of thin-films and hetero-structures. SrRuO3 thin film has been found to exhibit interesting spin-polarization behaviors. It is chemically stable and forms an excellent interface with Al2O3, and has therefore attracted much attention in the application of spin-dependent devices. In our previous study of Nd0.5Ca0.5.xSrxMnO3, we revealed its wealth of magnetic transformations and charge-ordering properties. The aim of this proposed study has three folds: (1) to make thin films of these materials with various deposition techniques and to study their magneto-transport properties in a systematic pattern; (2) To facilitate hetero-structures consisting of different combinations of ferromagnetic metals, normal metals, and ferromagnetic oxides. The long range coupling strength between (ferromagnetic metal/ oxide) and (oxide/ oxide) pairs will be explored by means of both in-plane and CPP (current-perpendicular-to-plane)-magnetoresistance experiments. (3) To study the structural and magnetic properties of interfaces where ferromagnetic oxide and metal are adjacent to each other. Their impact on the transport behavior of the hetero-structure will be investigated in details.
