鈷/鉑多層薄膜與鈷鉑合金膜之製備與性質研究

Abstract

本篇論文，為探討高垂直異向性的鈷/鉑多層薄膜及其合金之製備方法， 並建立材料微結構與磁╱磁光性質的關係。同時，測試鈷鉑合金碟片，以 做為磁光記錄媒體可行性的研究。 以雙電子鎗蒸度系統及濺鍍系統製備 鈷/鉑多層薄膜，其層狀結構可由低角度的X 光繞射結構証明；當鈷層厚 度約3埃時，具有最大的垂直異向性。 利用氧化鋅及氧化鎵底層，可以有 效地增加鈷/鉑多層薄膜的保磁力；且保磁力隨柱狀結構(以原子力掃描顯 微鏡(AFM)觀察)的大小而變化。這項關係可利用"磁性獨立柱狀體"的模型 來解釋。除此以外，退火處理後的磁性質改變也一併討論。 由濺鍍系統 成長鈷鉑合金薄膜，在基板溫度200~250oC，及鈷組成25%的最佳條件下 ，可獲得具有保磁力2.4KOe，方形度100%之垂直異向薄膜。由穿透試電子 顯微鏡觀 察合金薄膜，主要的缺陷為退火孿晶，且在最佳條件下，孿晶 的數目最多。在CoPt3部分序化，孿晶及鈷─鈷對的形成假設下，由配位 模型(Pair Model)計算出異向方向垂直孿晶平面。 單層鈷鉑合金碟片經光碟測試機，以波長680nm雷射光為光源，於1MHz ，10M/s切線速度，可獲得訊號雜訊比~45dB，碟片寫入功率約需10mW，外 加磁場約需300 Oe。 Co/Pt multilayers and alloy films with large perpendicular anisotropy have been fabricated, and the correlations between their magnetic/magneto-optic properties and microstructures were investigated. A disk made of the CoPt alloy film was characterized for the feasibi-lity as a media of magneto-optic recording.Co/Pt multilayers were prepared by evaporation and sputter methodswith dual-guns. The layered structure was manifested by low angle x-ray diffraction. The highest perpendicular anisotropy was obtained inthe films of Co thickness ~3A.ZnO and Ga2O3 underlayers enhanced effectively the coercivity of Co/Ptmultilayers. The dependence of the measured coercivity on the columnsize (characterized by AFM) was interpreted based on a model of magne-tically independent columnar particles. The annealing effects on magnetic properties were also studied.CoPt alloy films grown at the optimized conditions, 200~250oC with Cocontents 25%, exhibited perpendicular coercivity ~2.4 KOe and a saturated remanence. By TEM analysis, the major defects detected inthe films were twins and the highest concentration of twins was foundin the optimized sample. Assuming the partial ordering of CoPt3, twins and Co-Co pairs, induced anisotropy normal to twins-plane was evalu-ated by a Pair model.Disk coated with the CoPt alloy films was tested, using a laser sourceof wavelength 680 nm, at 1 MHz recording frequency and 10 M/s velocity, CNR~45 dB was obtained with a recording power ~10mW and external field ~300Oe.