氧退火處理對FePt:B薄膜性質改善及FePt:C/B之雙層結構提升柱狀晶成長之研究

Oxygen post-annealing treatment on FePt:B films & promoted columnar grain growth in FePt:C/FePt:B bilayer structure

黃上碩(Huang, Shang Shuo)

指導教授 ： 賴志煌

國立清華大學/工學院/材料科學工程學系/碩士(2015年)

摘要

FePt具有高的磁晶異相性及高矯頑場，被認為是次世代硬碟的熱門選擇。對於以L10 FePt 為基材的微粒狀紀錄媒體而言，B添加可以達到良好的微觀結構。然而故溶於FePt中的B會影響其序化行為，提升FePt的序化溫度。在本實驗的第一個部分，我們將初鍍膜的FePt:B薄膜在氧氣氛下進行後退火，發現在高溫的環境下，氧氣可以改善FePt:B的微觀結構及磁性質，使FePt:B有良好的(001)優選取向，及接近6奈米的晶粒尺寸。另一方面，C添加被認為是一個具有潛力的析出物材料選擇，其原因在於有良好的晶粒尺寸及磁性質表現。然而C會在FePt的晶粒表面析出妨礙柱狀晶成長。在本實驗的第二個部分，利用FePt:B (30 vol. %) 及FePt:C (28 vol. %)的優點，以FePt:C/FePtB的雙層結構，我們可以得到良好的晶粒分隔性及柱狀晶成長，而不破壞其序化，造成磁性質的劣化。藉由最佳化其成分及厚度，我們可以得到晶粒尺寸為6.92奈米及深寬比為1.44。本實驗利用同步輻射XPS觀察到B、C之間的鍵結，我們認為此鍵結是造成磁性質及為結構改善的主要原因。

關鍵字

磁紀錄媒體 ； 硬磁材料 ； 序化鐵鉑合金 ； 微粒狀結構

並列摘要

FePt has drawn lots of attention for the next-generation perpendicular magnetic recording media because of its large magnetocrystalline anisotropy. For L10 FePt-based granular recording media, the desired granular structure can be achieved by the addition of boron. However, the residual boron in FePt grains retards the L10 ordering. In first part, we introduce an additional post-annealing process in the oxygen atmosphere after the deposition of FePt:B films. We show that oxygen is capable of improving the boron segregation and therefore yields the granular and L10 ordered FePt films with the (001) orientation. In the other hand, C addition was reported as a promising segregant to obtain a small grain size of 6 nm with good L10 ordering and (001)-oriented FePt grains.However , the segregation on the top of FePt leads to a second layer of FePt grains with (111) orientation. In second part, we used bilayer composed of FePt:B (30 vol. %) and FePt:C (28 vol. %) films to take advantage of two segregants.By optimizing thickness of FePt:C and FePt:B we gets a good isolated granular structure with promoted columnar growth grain of 6.92 nm and aspect of 1.44 . We shows that the FePt:C template layer is able to retrieve the ordering in FePt:B by forming the B-C phase which is investigated by Synchrotron Radiation XPS.

並列關鍵字

Recording media ； hard magnetic material ； L10 FePt ； granular structure

參考文獻

[9] L. Zhang, Y. K. Takahashi, A. Perumal, and K. Hono, J. Magn. Magn. Mater. 322, 2658 ,2010.

[32] Chang, C. W., et al. Journal of applied physics , 97.10 , 10N117-10N117,2005.

[39] Chiu, J. C., Wen, W. C., Wang, L. W., Wang, D. S., & Lai, C. H. Journal of Applied Physics, 115(17), 17B713 ,2014.

[49] Chiu, J. C., Wen, W. C., Wang, L. W., Wang, D. S., & Lai, C. H. Journal of Applied Physics, 115(17), 17B713, 2014.

[38] Ding, Y. F., Chen, J. S., & Liu, E. Applied Physics A, 81(7), 1485-1490 ,2005.