Abstract We study numerically the exchange bias effect in thin cylindrical nanowires composed of a ferromagnetic core and an antiferromagnetic shell implementing a classical spin Hamiltonian and Monte Carlo simulations. We address systematically the effect of shell polycrystallinity on the characteristic fields of the isothermal hysteresis loop (coercivity, exchange-bias) and their angular dependence upon the direction of the reversing and cooling fields. We relate the observed trends to modifications of the underlying magnetization reversal mechanism. We fit our simulation results to an extended Stoner-Wohlfarth model with effective off-axis unidirectional anisotropy and demonstrate that shell polycrystallinity leads to maximum exchange bias effect in an off-axis direction. Our results are in qualitative agreement with recent experimental studies of Co/CoO nanowires.

中文翻译：

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具有铁磁芯和多晶反铁磁壳的圆柱形纳米线中的交换偏置效应

摘要 我们数值研究了由铁磁芯和反铁磁壳组成的细圆柱纳米线中的交换偏置效应，实现了经典的自旋哈密顿量和蒙特卡罗模拟。我们系统地解决了壳多晶性对等温磁滞回线的特征场（矫顽力、交换偏置）的影响及其对反向和冷却场方向的角度依赖性。我们将观察到的趋势与潜在磁化反转机制的修改联系起来。我们将模拟结果拟合到具有有效离轴单向各向异性的扩展 Stoner-Wohlfarth 模型，并证明壳多晶性导致离轴方向上的最大交换偏置效应。