Shape- and thickness-dependent magnetization reversal process is investigated in CoFe nanostructures by micromagnetic simulations. The reversal is abrupt in the case of 10-nm and 20-nm thick rectangular and square nanostructures. Intermediate double vortex states are formed in rectangular nanostructures of thickness 30 to 60 nm when the field is applied along the longer dimension. Magnetization reversal along the shorter dimension happens through the formation of multivortex states. Similar type of reversal is observed in 40 to 60-nm thick square nanostructures of dimensions 225 nm and 335 nm.

中文翻译：

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矩形和方形CoFe纳米结构在磁化反转过程中的多涡形成

通过微磁模拟研究了CoFe纳米结构中形状和厚度相关的磁化反转过程。在10nm和20nm厚的矩形和正方形纳米结构的情况下，这种反转是突然的。当沿较长的方向施加电场时，在厚度为30至60 nm的矩形纳米结构中会形成中间双涡旋状态。沿较短维度的磁化反转通过形成多涡旋状态发生。在尺寸为225 nm和335 nm的40至60 nm厚的方形纳米结构中观察到相似类型的逆转。