具有Dzyaloshinskii-Moriya作用的磁性薄膜系統之微磁學研究

The Micromagnetic Study of the Magnetic Thin Film Systems with Dzyaloshinskii-Moriya Interaction

邱宛娜(Silviana Simbolon)

指導教授 ： 吳啟彬

中原大學/理學院/物理研究所/碩士(2016年)

https://doi.org/10.6840/cycu201600482

摘要

本論文利用Mumax3與OOMMF這兩個微磁學模擬軟體對具有Dzyaloshinskii-Moriya interaction（簡稱DMI) 性質的磁性薄膜進行磁性行為的研究。外加磁場的範圍在 0 到 3 特斯拉之間，方向為垂直 薄膜表面。在這些參數下，磁性薄膜展現具有特殊旋性的結構，例如混合（條狀磁區和磁孤子skyrmion共存的狀態），磁孤子態等。在外加垂直磁場下，當DMI強度增加的時候，磁孤子數（skyrmion number）也會跟著增加。磁孤子的大小會受到DMI強度以及外加磁場的大小改變。對於磁易向軸平行薄膜面的磁性薄膜來說，施加平行膜面的磁場並不會導致磁孤子態的產生。在較強的DMI下，樣品會出現的磁旋態為條狀擺線旋進態（cycloidal phase）、半磁孤子態（meron）。半磁孤子態的產生是因為條狀磁區被強大的DMI所破壞。本論的研究結果對於要產生不同的磁旋態所需要的DMI強度與磁場強度有很大的幫助。

關鍵字

微磁學模擬 ； OOMMF ； Mumax3 ； DMI ； skyrmion ； 磁薄膜

並列摘要

In this thesis, the behaviour of the magnetic thin film with Dzyaloshinskii-Moriya (DM) interaction is investigated by micromagnetic simulations such as MuMax3 and OOMMF. For the system, an external magnetic field between 0-3 Tesla is applied perpendicular to the thin film. This condition generates chirality phase such as mix state (stripe + skyrmion) and isolated skyrmion phase. Value of skyrmion number increases as DM interaction and the external magnetic field. Diameter of skyrmion is influenced by DM interaction and the external magnetic field. Diameter of skyrmion is larger by DM interaction and smaller by the external magnetic field. When the magnetic field is applied parallel to the thin film, it is observed that skyrmion phase cannot exist in this system. The chirality phases which are governed by large DM interaction are such as cycloid phase and half-skyrmion (meron) phase. Merons occur due to cycloid stripe being broken by large DM interaction. The result of this thesis also presents impact of the simple size on the range of DM interaction and the external magnetic field, which are needed for getting chirality phases. The results of the thesis can be used for developing the spintronic devices based on the skyrmions or cycloids.

並列關鍵字

Dzyaloshinskii-Moriya interaction ； skyrmion ； meron ； MUMAX3 ； OOMMF

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