Micromagnetic Analysis of Field-assisted Magnetic Skyrmion Nucleation in Co/Pd Multilayer

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/97790

Title:	Micromagnetic Analysis of Field-assisted Magnetic Skyrmion Nucleation in Co/Pd Multilayer
Authors:	黃岱陞;Huang, Tai-Sheng
Contributors:	物理學系
Keywords:	斯格明子;微磁學模擬;鈷/鈀多層膜;反對稱交換作用;拓撲電荷;Skyrmion;Micromagnetic Simulation;Co/Pd Multilayer;Dzyaloshinskii–Moriya Interaction;Topological Charge
Date:	2025-07-22
Issue Date:	2025-10-17 11:54:29 (UTC+8)
Publisher:	國立中央大學
Abstract:	磁性斯格明子 (Skyrmion) 是一種具有拓樸保護的自旋結構，因為可於室溫下以奈米尺度穩定存在且易於操控等特性，在自旋電子學領域中受到關注。特別是具有垂直異向性 (PMA) 與界面Dzyaloshinskii–Moriya interaction（DMI）的鐵磁/重金屬多層膜系統，被視為下一代非揮發性記憶體以及邏輯元件的潛力材料。儘管已有不同研究探討過不同磁性參數對於磁斯格明子的穩定性，考慮了熱擾動及調控外加場下的動態過程中，磁斯格明子的生成/湮滅機制仍續更進一步的分析。本研究以Co/Pd多層膜系統進行微磁學模擬分析，透過與實驗量測的磁滯曲線與磁力顯微鏡（MFM）圖像比對，擬合出有效磁異向性常數與界面 DMI 強度，建立可重現外加磁場調控下實驗趨勢的模擬模型。接下來，進一步模擬不同樣品厚度下的磁結構變化，繪製出磁異向性與外加場條件下的相圖，明確指出斯格明子穩定存在的區域與磁結構相轉變的邊界。此外，我們透過理想模型下的能量分析與 Arrhenius 定律，量化熱擾動激發下高磁場區域磁斯格明子的湮滅以及低磁場區域磁化反轉的過程所需的能障，指出了數值模擬的時間尺度與熱擾動共同決定了轉變邊界在相圖中的位置。本研究建立一套自洽的模擬與分析框架，幫助理解場輔助磁斯格明子的生成與湮滅機制與熱穩定性，可作為未來拓撲磁結構應用與設計的參考。;Magnetic skyrmions are topologically protected spin structures, which received significant attention in the field of spintronics due to their nanoscale size at room temperature and easy to manipulate. In particular, FM/HM multi-layers system with strong perpendicular magnetic anisotropy (PMA) and interfacial Dzyaloshinskii–Moriya interaction (DMI) are regarded as promising candidates for next generation Non-volatile memory and logic device. While several studies have investigated how different magnetic parameters affect skyrmion stability, the dynamics processes of skyrmion’s nucleation/annihilation involves thermal fluctuations and field modulation still require further analysis. In this study, we focus on the micromagnetic simulations on Co/Pd multilayer systems. By fitting experimental hysteresis loops and images from magnetic force microscopy (MFM), we determine the effective anisotropy constant and interfacial DMI strength, reproducing the field assists skyrmion nucleation behavior from the experimental trends. Then, we further simulated the differences in magnetic domain pattern under different sample thickness and constructed a phase diagram with respect to anisotropy and external magnetic field, identifying the existence windows for skyrmion state and the domain pattern’s phase transition boundary. Moreover, we apply energy analysis and Arrhenius law to quantify the energy barriers associated with skyrmion annihilation under high fields conditions and magnetization reversal under low fields, revealing how thermal energy and simulation timescale determine the phase boundary positions. This work established a self-consistent simulation and analysis framework that provides a useful reference for the design of future skyrmion-based spintronics devices.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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