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| 题名: | 新穎微小磁盤結構中渦漩核心受微波激發鐵磁共振之研究
Experimental and Simulation Study on Microwave Excited Ferromagnetic Resonance of Vortex Core in Novel Magnetic Disk Structures |
| 作者: | 鄧景華 |
| 贡献者: | 李尚凡
Lee, Shang Fan
鄧景華 |
| 关键词: | 渦漩核心
鐵磁共振
磁盤
Vortex Core
Ferromagnetic Resonance
Magnetic |
| 日期: | 2015 |
| 上传时间: | 2015-08-03 13:31:17 (UTC+8) |
| 摘要: | 本論文分為三部分，第一部分探討垂直方向微波進入微米三層膜結構磁盤中渦漩態和其他暫穩態耦合鐵磁共振激發，以往文獻中指出高頻率(GHz)在垂直方向會誘發微小磁盤中渦漩核心產生激發，但因垂直方向磁矩變化量相對整體磁矩的值較小，在實驗上不易測量。本實驗我們利用微小磁盤的三層膜結構鎳鐵/銅/鎳鐵(Py/Cu/Py)來探討渦漩態和其他亞穩態耦合鐵磁共振，在其他亞穩態的幫助下，我們可以更容易量測到垂直方向微波激發渦漩核心的間接訊號，並且使用OOMMF磁性材料模擬軟體來模擬各種亞穩態和渦漩核心耦合的情形。
第二部分，為利用形狀異相性(Shape anisotropy)製作「凸字形」的同心圓磁盤，使渦漩態中渦漩核心周圍磁矩的垂直分量增加，並探討渦漩核心移動時的磁阻變化。利用OOMMF磁性材料模擬軟體，模擬中我們可以看到渦漩核心受到垂直方向的微波激發除了上下震盪之外，還誘導出了水平方向渦漩核心的螺旋形移動。實驗中量出磁盤的異向性磁阻，搭配利用高頻訊號產生器給予磁盤垂直方向微波測量，我們利用這些量測解釋渦漩核心運動情形，驗證渦漩核心受到垂直方向激發之後會產生水平方向的移動。
第三部分，利用OOMMF發現到在垂直異相性(Perpendicular Magnetic Anisotropy)的磁盤薄膜中，利用水平方向的變頻微波擾動，可以使原本垂直異相性的薄膜變成Skyrmion態。在現有的文獻之中，除了晶格異相性(Magnetocrystalline anisotropy)可以產生Skyrmion態，人造的部分一直遲遲未找到。因此我們製作了Pd/Co多層膜製作自旋閥的結構，對於未來製作出人造的Skyrmion有很好的開始。
We report experimental detection of the behaviors of magnetic vortex cores using out-of-plane (electro)-magnetic fields that oscillates at the eigenfrequencies of novel permalloy magnetic disk structures.
First, We study interlayer-coupled magnetic vortex core and different stable excitation states in resonant perpendicular magnetic field of permalloy(Py)/Cu/Py trilayer disks. The samples are Ta(10)/Py(10)/Cu(3)/Py(25) (thickness in nm) disks of 2μm diameter, patterned via electron-beam lithography. When the samples are located in the gap of ground-signal-ground (GSG) coplanar waveguide, a high-frequency out-of-plane magnetic field (H_r ) is generated by a radio frequency signal generator. When the samples are located on the signal line of the GSG waveguide, in-plane resonant fields (H_t) is applied transversely. We show that by using a sequence of H_t and H_r, different ferromagnetic (FM) layer resonant states can be controlled in a systematic way. We observed several peaks between 5 GHz and 7 GHz, which were sensitive to the field.
Secondly, we study the vortex core excitation of out-of-plane precession motion accompanied with in-plane precession induced by shape anisotropy in resonant perpendicular magnetic field of two-magnetic-disk structures. The samples are Py(10)/Py(40) disks of 1μm/2μm diameter, patterned via electron-beam lithography. We show that by using a sequence of H_t and H_r, the vortex core is excited into in-plane precession motion after out-of-plane precession in resonant perpendicular magnetic. We observed a peaks near 7 GHz, which were different from different position and out-of-plane resonant field intensity.
Lastly, we created skyrmion state by micromagnetic simulation using an in-plane frequency conversion (0Ghz~50GHz) in perpendicular magnetic anisotropy (PMA) materials. In the future, we can use Giant Magnetoresistance (GMR) in spin valve structures to detect the formation of skyrmions experimentally. |
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| 描述: | 碩士
國立政治大學
應用物理研究所
102755002 |
| 資料來源: | http://thesis.lib.nccu.edu.tw/record/#G0102755002 |
| 数据类型: | thesis |
| 显示于类别: | [應用物理研究所 ] 學位論文
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