錳鈷雙層的磁異向能和交換偏耦合

Magnetic Anisotropy and Exchange Coupling in Mn/Co Bilayer System

陳倫佳(Lun-Jia Chen)

指導教授 ： 林敏聰

國立臺灣大學/理學院/物理研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10662

摘要

在塊材材料中，面心立方的錳存在於1368 K 和1406 K 之間。透過分子束磊
晶的技術，面心立方的錳可以成功地在室溫下成長在鈷/銅(001)上，由於在界面
上微小的晶格不合。錳膜隨著厚度的改變會造成結構從面心立方過渡到延展的面
心體立方。
透過低溫自旋極化掃瞄穿隧顯微鏡和磁光柯爾效應的測量，研究磁域結構和
磁滯曲線的特性。
利用低溫自旋極化掃瞄穿隧顯微鏡，解出延展面心體立方結構錳膜的平行面
層狀反鐵磁自旋結構。越過台階，沿著錳邊緣觀察到自旋擾動。除此之外，在室
溫下透過平行面的磁光柯爾效應，外加場沿著鈷膜易軸方向，在較薄錳膜時，殘
餘磁化量和矯頑磁場兩者都隨著錳厚度下降；越過臨界厚度時，矯頑磁場開始增
加。殘餘磁化量的下降仍被觀察到。
除了錳厚度變化之外，我們也比較了不同溫度下的磁光柯爾效應量測的磁性
行為。

關鍵字

交換偏耦合,磁異向能

並列摘要

In bulk material, Face-centered-cubic (fcc) Mn exists between 1368 K and 1406
K. Through the technique of molecular beam evaporation (MBE), fcc Mn can be
successfully grown on Co/Cu(001) at 300 K (RT), because of the small lattice mismatch
at the interface. Mn lms proceed a thickness-dependent structural transition
from face-centered-cubic (fcc) to expanded face-centered-tetragonal (e-fct).
From the low temperature Spin-Polarized Scanning Tunneling Microscopy (SPSTM)
and Magneto-Optical-Kerr-E ect (MOKE) measurements, the magnetic domain
structure and hysteresis loop properties have been studied.
By using the low temperature SP-STM, the in-plane layered antiferromagnetic
spin structures of such e-fct Mn has been resolved. Across the terrace, the spin
frustration can be observed along the Mn edge. Besides, from the in-plane MOKE
measurement at room temperature, with the external eld applied along the easy
axis of the Co lm, both the remanence magnetization (Mr) and coercivity (Hc)
decrease at thinner layers of Mn in the beginning and the (Hc) starts to increase
after acrossing the critical Mn thickness. A correlated decrease of (Mr) is observed.
In addition to the Mn thickness dependence, we also compare the di erent magnetic
behavior in the temperature dependence of MOKE measurement.

並列關鍵字

Exchange Coupling,Anisotropy

參考文獻

[1] Nogues J and Schuller I K, J. Magn. Magn. Mater., 192, 203. (1999).

[2] J. Hafner and D. Spi s ak, Phys. Rev. B 72, 14420. (2005).

and Minn-Tsong Lin, Phys. Rev. B 75, 054419. (2007).

[4] Heinrich B, Arrott AS, Liu C, and Purcell ST., J Vac Sci Technol A 5, 1935.

[5] J. T. Kohlhepp and W. J. M. de Jonge, Phys. Rev. Lett. 96, 237201. (2006).