銀／鐵／銀／鉑（111）奈米多層超薄膜磁性研究

由於鐵與銀的介面磁異向性能作用使得銀／鐵／鉑（111）超薄膜系統發生電子自旋指向轉變（SRT），其磁化易軸從平行表面方向轉變為垂直表面方向，當銀覆蓋厚度達到lML時；垂直方向的磁化強度與矯頑力兩者同時皆達到最大值。現以2ML鐵／1.4ML銀／鉑（111）為系統基底，再蒸鍍上不同原子層數的銀薄膜，使用表面磁光柯爾效應儀（SMOKE）探測XML銀超薄膜覆蓋於2ML鐵／1.4ML銀／鉑（111）樣品前後之表面磁性變化，並藉由歐傑電子能譜術（AES）鑑別樣品表面組成成分、計算薄膜厚度，以及低能量繞射電子儀（LEED）研究表面結構變化，結果發現其垂直方向的磁化強度未因銀薄膜覆蓋的增加而增加，其磁化易軸一直保持在平行表面方向。因為鐵與銀的表面自由能差因素及原子晶格不匹配度過大而造成介面的不平整性，使其鐵與銀的介面磁異向性能大幅減少以至無法產生電子自旋指向轉變現象。在0～0.35ML銀／2ML鐵／1.4ML銀／鉑（111）系統時其飽和磁化量（Ms）快速下降，可能是由於蒸鍍上的銀原子形成奈米島，其台階原子上之電子轉移較大，對磁性有壓制的現象。

關鍵字

表面磁光柯爾效應；表面磁異向性能；鐵；銀

並列摘要

By the Ag/Fe interface magnetic anisotropy, the spin-reorientation transition (SRT) is observed on the ultrathin films Ag/Fe/Pt(111) system. The easy axis of the magnetization changes completely from the in-plane to out-of-plane direction after l ML of Ag coverage. Both the polar Kerr intensity and perpendicular coercivity have their maximal value when the thickness of Ag thin film layer has arrived 1 ML. Now we use combined in situ MOKE and AES to investigate the effect of the Ag capping layers on the magnetic properties of Fe/Ag/Pt(111) films at room temperature. The polar Kerr intensity does not significantly change when the Ag overlayers are capped, the direction of easy magnetization axis is in the sample plane. The growths of Ag/Fe and Fe/Ag are in a 3-D island growth mode at room temperature. This is due to the effect of the surface free energy and the large lattice mismatch between Fe and Ag atoms. The interface magnetic anisotropy of Ag/Fe interface is reduced too weak to induce SRT. The saturated magnetization (Ms) is reduced significantly when the 0～0.35 ML Ag is capped on 2 ML Fe/1.4 ML Ag/Pt(111) system. The transformation of electric on the atomic step is more strength from silver nano-islands may be the mechanisms of the restrain of interface magnetic anisotropy.