利用磁力探針顯微鏡測量氧化鋅參雜鈷奈米線的磁力性質

Abstract

本實驗利用磁力探針顯微鏡觀察氧化鋅參雜鈷奈米線的磁力性質，相對於超導量子干涉儀只能測量材料的整體性質，磁力探針顯微鏡具有測量單根奈米線的特性。我們利用硬碟碟片的測試示範了儀器參數的選取對於磁力影像的影響，並界定出掃描奈米線所適合的參數。我們利用離子佈植方法把不同濃度的鈷試片打入氧化鋅奈米線之中。得到了Zn0.98Co0.02O，Zn0.95Co0.05O，Zn0.91Co0.09O，Zn0.87Co0.13O等等不同參雜濃度的奈米線材料。並選取佈植能量為40kev以及鈷參雜濃度為12.8%的氧化鋅奈米線作為測量的樣品。為了提高奈米線的鐵磁性，我們將奈米線在氣壓為4×10-5的環境以873k的溫度作六個小時的退火處理。這使得奈米線內的氧空缺增加並進一步的提高奈米線的鐵磁性性質。 我們利用磁力探針顯微鏡觀察到氧化鋅參雜鈷奈米線具有室溫鐵磁性質，並從磁力影像中得知大部分的易軸方向垂直於奈米線成長方向。並也發現在某些奈米線中具有多個磁區的分佈。我們也統計了不同直徑的奈米線並發現並不完全符合預期的尺寸效應，這是由於經由激發光螢光機制測量不同直徑的奈米線可以發現奈米線內部的缺陷和奈米線的直徑成反比，由於氧空缺的增加使得奈米線的鐵磁性變強，因此奈米線的磁力並不會和直徑的兩次方成正比。

We use Magnetic Force Microscopy to observe magnetic property of Zn1-xCoxO nanowires. Compare with SQUID,Magnetic Force Microscopy can measure individual nanowires. We measure the hard disk for the example of the relation between work-parameter and magnetic image, and we confirm the fit parameter for scanning nanowire. We implant different concentration of Cobalt into ZnO nanowires by ion implanting. We can get the Zn1-xCoxO nanowire for different concentration of cobalt as Zn0.98Co0.02O, Zn0.95Co0.05O, Zn0.91Co0.09O , Zn0.87Co0.13O nanowires. We select Zn0.87Co0.13O nanowires which has implanted by 40kev.because we want to increase the ferromagnetism of nanowires, we annealed nanowires at 873k in vacuum 4×10-5pa for 6h.It can increase numbers of oxygen vacancy to increase the ferromagnetism of Zn0.87Co0.13O nanowires. We have observed the room-temperature ferromagnetism of individual Zn1-xCoxO nanowires by Magnetic Force Microscopy. Most of our phase images revealed both dark and bright domains along the edges of the shorter nanowires, implicating that the magnetization is perpendicular to the growth direction of shorter nanowire . we also have observed multi-domain on the nanowires. The statistical result of the phase difference presents the roughly linear dependence on the nanowire diameter. It’s not conform to the size effect because of the oxygen vacancy.