透過氫氣作用控制磁性層間交互耦合效應

Abstract

長期以來，鈀一直作為氫氣解離和吸附的高效催化劑。在鈀合金或內米結構中，鈀的氫化容易引起相鄰材料有顯著的鄰近效應。在本實驗中，我們在超高真空中使用電子束蒸發磊晶法，在MgO (001)的基底上製備了磁性界面耦合系統。通過退火處理，可以得到平坦的MgO (001)表面，用來沉積Fe/Pd/Fe三層膜。 在一定鈀的厚度下，通過磁光柯爾效應在平行(In-Plane)方向，可以在Fe/Pd/Fe/MgO(001)系統中觀察到清楚的雙磁滯曲線。這現象說明頂層和底層鐵層之間的反鐵磁耦合。隨著室溫下的氫氣脫吸附，反鐵磁層間耦合有明顯的變化，如雙磁滯曲線的矯頑場變化所示。這結果表示，鐵/鈀多層膜系統未來可以應用為敏感性高的氫氣感測GMR傳感器

Pd has long been used as a high efficient catalyst for hydrogen dissociation and absorption. In the Pd-alloys or nanostructures, the hydrogenation of Pd easily brings in pronounced proximity effect upon the adjacent functional materials. In this experiment, we prepared the magnetic exchange interlayer coupled system, Fe/Pd/Fe trilayers, on MgO(001) substrates using e-beam evaporation in an ultrahigh vacuum. Through a suitable annealing process, a flat MgO(001) surface can be achieved for the deposition of the Fe/Pd/Fe trilayer. With a certain Pd thickness, clear double hysteresis loops were observed in the Fe/Pd/Fe/MgO(001) system by using magneto optical Kerr effect in the in-plane direction. This indicates the antiferromagnetic coupling between the top and bottom Fe layers. With cyclic hydrogen absorption and desorption at room temperature, the antiferromagnetic interlayer-coupling was considerably and reversibly changed, as indicated by the change of the shift field of the double loops. This observation suggests that the Fe/Pd-multilayer system can serve as a GMR sensor for sensitive hydrogen sensing in the future applications.