( 1. 中南大學 物理科學與技術學院， 長沙 410083;
2. 中南大學 粉末冶金國家重點實驗室， 長沙 410083)
摘 要: 通過微磁學模擬手段對長徑比均為10的不同直徑納米線的反磁化機制進行了系統(tǒng)研究， 發(fā)現(xiàn)磁反轉模式強烈地依賴于納米線的直徑。 直徑很小時， 反轉模式為一致反轉； 隨著直徑增大， 反轉模式過渡為兩種不同類型磁化核(一致截面的磁化核或渦旋截面的磁化核)的形成與傳播； 對于更大直徑的納米線， 納米線中出現(xiàn)多疇結構， 反轉過程通過多疇渦旋中心的移動來實現(xiàn)， 渦旋中心的移動滿足右手定則； 得到了各種反磁化機制過渡的臨界尺寸。 計算了不同直徑納米線的矯頑力， 并與實驗數(shù)據(jù)進行了比較， 從反磁化機制的角度解釋了矯頑力隨直徑的變化關系。
關鍵字: 納米線; 微磁學; 反磁化機制
（ 1. School of Physics Science and Technology,
Central South University, Changsha 410083, China;
2. State Key Laboratory of Powder Metallurgy,
Central South University, Changsha 410083, China）
Abstract: The magnetization reversal mechanism of magnetic nanowires with different diameters but the same aspect ratio 10 were investigated by micromagnetic simulation. The results show that the reversal mechanism significantly depends on the nanowire diameter. For the smallest wire, the reversal model is coherent rotation . With the increase of diameter, magnetization reversal takes place via different nucleation (the transverse domain wall or the vortex domain wall) and subsequent propagation. For the larger nanowire, multidomain will form within the wire, the magnetization reversal is determined by the motion of vortexs which comforms to the right hand rule. The critical diameters of different reversal mechanism are obtained. The coercivities of nanowires with different diameters are calculated and compared with experimental data, the change of coercivity with diameter is interpreted in terms of magnetization reversal mechanism.
Key words: nanowire; micromagnetics; magnetization reversal mechanism
