透過界面工程探討並實現界面與層間反對稱交互作用的連結與線性調控

Abstract

近年來，自旋電子學的相關研究，已經慢慢從線性的磁性行為延伸到非線性的作用。其中，尤其是層間Dzyaloshinskii–Moriyainteraction (IL-DMI)，因為其在鐵磁層間控制長距離手性耦合的能力而備受矚目。然而，這種作用一直缺少了微觀尺度下的解釋，特別是與已經有較完整研究歷史的InterfacialDMI(IF-DMI)相比。釐清IL-DMI與IF-DMI之間的關係對於控制對手性磁矩排列來說是至關重要的。 為此，我們藉由改變T型結構中由鈷,鎳與鉑組成的垂直排列(PMA)鐵磁層排列方式，展示了明確的IL-DMI極性反轉現象。這個磁性的極性反轉的過程是從鈷金屬主導轉變成鎳金屬主導。更透過控制與鉑接觸的金屬，來判斷這個 IL-DMI 的極性轉換是源自於鐵磁層與鉑的界面效應，而非鐵磁層厚度變化導致。 再者，我們也透過方正的無場翻轉，來驗證這個翻轉的極性是真的跟著IL-DMI 的機制走的。接著我們利用非常薄的鈷介入磁性薄膜與鉑金屬的中間層，發現了極為顯著的翻轉電流密度下降，從4.45×107A/cm2下降到1.39×107A/cm2。這些發現不僅凸顯了界面材料組合在調控磁性多層膜手性耦合中的重要性，並透過界面驅動的IL-DMI線性調控，展示一條通往低功耗自旋軌道力矩元件的可行途徑。

In recent years, spintronics research has evolved from collinear to noncollinear magnetism, stimulating growing interest in the interlayer Dzyaloshinskii–Moriya interaction (IL-DMI) as a mechanism for long-range chiral coupling between magnetic layers. Despite its importance, the microscopic origin remains unclear, particularly regarding the extensively studied interfacial DMI (IF-DMI). Establishing whether these two forms share a common physical origin is crucial for the unified control of chiral spin textures in engineered heterostructures. Here, we demonstrate a clear polarity reversal of IL-DMI by tuning the ferromagnetic composition of the perpendicularly magnetized layer in a type-T structure consisting of Co/Ni and Pt. The polarity reversal coincides with a transition from a Co-dominated to a Ni-dominated interface. Control experiments further reveal that the IL-DMI direction is governed solely by the identity of the ferromagnetic layer directly interfaced with the Pt spacer, and is largely independent of the total ferromagnetic thickness. Furthermore, robust field-free switching is achieved, with the switching polarity directly determined by the IL-DMI sign. By engineering the interfacial configuration through ultrathin Co insertion, we achieve a substantial reduction in the switching current density, with JSOT decreasing from 4.45 × 107 A/cm2 to 1.39 × 107 A/cm2. These results establish interfacial composition as a key tuning parameter for chiral coupling in spintronic multilayers and provide a practical pathway toward energy-efficient spin–orbit torque devices enabled by interface-driven control of IL-DMI.