摘要
我們在此研究課題使用L11-CoPt二元合金薄膜(具有垂直異向性的硬磁層)與NiFe薄膜(具有水平形狀異向性的軟磁層)形成的雙層膜結構上，探討磁交互耦合彈簧，並藉由軟磁與硬磁界面交換耦合造成傾斜的磁異向性中，改變界面交換耦合的形式可用來調整軟磁層磁化方向傾斜的程度，形成可調式傾斜角度磁化方向的薄膜系統。在實驗中所使用樣品皆使用磁性濺鍍的方法，並以玻璃為基板加上20奈米厚Pt底層作成。 為了掌握此研究課題要點，我們經由對L11-CoPt垂直硬磁層與NiFe軟磁層各自作完整製程與磁性研究，確定可以掌握其各層磁性薄膜特性後，開始進行以下三大方向來進行實驗: (1) 改變NiFe的厚度，但不改變L11-CoPt的厚度。 (2) 改變L11-CoPt的製程溫度，但NiFe的製程溫度都控制在室溫。 (3) 在CoPt與NiFe間插入中間非磁性層(Pt或Ru)。 從以上三種方法我們證明出，1)可以調控磁矩的傾斜角度從小角度到75度的範圍；2)不同製程溫度的CoPt後與NiFe形成不同的界面交互耦合強度，造成NiFe層的磁矩顯現出不同的傾斜角度；3)透過Pt層除了可以得到急速隨Pt厚度增加變小的界面耦合強度外，NiFe磁傾斜角度很快增加成為顯現水平磁異向性；4)在Ru中可以得到界面耦合強度隨Ru厚度增加造成震盪的結果。磁交互耦合彈簧的研究證明可調式磁矩的L11-CoPt/NiFe雙層膜結構在未來可應用於三維磁感應器，或是需要傾斜式磁異向性極化層的電子自旋元件。
並列摘要
The exchange spring behaviors and title magnetic anisotropy were studied on L11-CoPt/NiFe bilayer systems. In this investigation L11-CoPt alloy film and Ni81Fe19 ( Permalloy ) films were exploited for the hard-layer with out-of-plane (OOP) and for the soft-layer with in-plane (IP) anisotropy, respectively. Through adjusting the interlayer exchange coupling between hard-layer and soft-layer, the tunable tilted magnetic anisotropy of the soft layer can be obtained. All the films studied herein were prepared by magnetron sputtering using glass as substrates along with a seed Pt layer of 20 nm. Before the L11 CoPt/NiFe bilayer systems were intensively investigated, the magnetic properties of bare L11 CoPt or NiFe layer were studied first. Afterwards three different approaches as shown below were adopted to investigate the exchange spring behaviors of L11 CoPt/NiFe bilayer systems: Varying the thickness of NiFe layer while keeping the thickness of L11 CoPt constant. Varying the deposition temperature of L11-CoPt layer while depositng the NiFe layer always at room temperature.. Inserting a nonmagnetic layer by using either Pt or Ru between L11 CoPt and NiFe layers. Our results reveal that the tilted magnetization angle of NiFe layer can be varied from 0° to 75°;Secondly, different processing temperature results in different interlayer coupling strength, casuing different magnetization tilted angle of NiFe layer; Third, the interlayer coupling strength decays rapidly as the thickness of Pt spacer is increased. The magnetization of NiFe is almost lying on the film plane when the thickness of Pt reachs 4 nm. Lastly, the two layer coupling strength as well as the tilted angle of NiFe layer oscillates with the thickness of Ru layer. The above results demonstrate that the tunable tilted exchange springs can be realized with L11-type CoPt/NiFe bilayers. Furthermore, the possibilities of future applications in three-axis magnetic sensors or advanced spintronic devices demanding inclined magnetic anisotropy polarizer are justified.