本研究是在超高真空環境下將鈷蒸鍍在銥(111)表面上，以歐傑電子能譜儀與表面磁光科爾效應儀對此超薄膜做表面組成及磁性的分析工作，觀察鍍膜表面上的成長行為與磁性研究，以及熱退火後的合金現象與磁性現象的變化。薄膜厚度在2原子層以下沒有磁滯現象，此時樣品為非鐵磁性，當薄膜厚度超過2原子層，在極向與縱向方向皆出現磁滯現象，樣品轉變為鐵磁性，且其磁化異軸不偏向於水平或垂直任一方向。選定一系列Co薄厚度進行加熱退火處理，發現在適當溫度熱退火後，縱向磁滯消失而極向仍有磁滯現象，我們發現Co-Ir系統中具垂直異向性，此特性深具工業上高密度記憶媒體開發之應用潛力。以3原子層Co/Ir (111)為例，以歐傑電子能譜儀觀察樣品表面組成變化，發現Co/Ir介面在450 K左右就有明顯的擴散現象，溫度愈高擴散效應也愈明顯，以表面磁光柯爾效應儀研究所形成之CoIr合金，發現此系統具垂直磁化。由離子濺射與歐傑電子能譜儀所得深度組成分析，可以驗證加熱退火造成Co往Ir(111)基底擴散。改變Co厚度系統化研究Co/Ir (111)超薄膜之退火效應，得到4個原子層以內，退火溫度低於900 K之磁性相圖，結果發現Co/Ir (111)系統之垂直磁異向性發生在溫度高於550 K之區域，這時Co/Ir合金化效應已經很明顯，垂直磁化之產生與CoIr合金之組成強烈相關，其機制將作深入討論。 Magnetic properties of ultrathin Co films deposited on a Ir(111) surface at ambient temperature have been studied using surface magneto-optic Kerr effect technique. For Co/Ir(111) films thinner than 2 monolayers (ML), there is not magnetic hysteresis and the films are nonferromagnetic. As the Co thickness increases to above 2 ML, hysteresis occurs on both the longitudinal and polar configurations. The preferred orientation of magnetization for the films is neither on the surface nor perpendicular to the surface plane. Systematic investigations of the Co/Ir(111) films shows that perpendicular magnetic anisotropy (PMA) occurs after applying annealing treatment for films thinner than 4 ML. These results show that the Co/Ir system exhibits large technological potential in the applications of magnetic recording materials. As an example, significant interdiffusion occurs after annealing at temperature above 450 K for 3 ML Co/Ir(111) as revealed from Auger electron spectroscopy. Annealing treatment at higher temperatures results in a larger intermixing of Co and Ir at the surface layers. PMA occurs as the Auger intensity ratio (ICo/IIr) decreases to about half of the original value of the as-deposited film. Systemic investigations for the magnetic anisotropy of Co/Ir(111) system reveal a magnetic phase diagram for Co thickness up to 4 ML and annealing temperature up to 900 K. Regions of nonferromagnetic, PMA, and ferromagnetic phases were resolved. The relations between PMA and surface composition has been identified.
