The metastable behaviour of two dimensional anisotropic Blume–Capel ferromagnet, under the influence of graded and stepped like variations of magnetic field, has been investigated by extensive Monte Carlo simulation using Metropolis single spin flip algorithm. Starting from the initial perfectly ordered state, reversal of magnetisation has been studied in presence of the field. Metastable lifetime or the reversal time of magnetisation for the system having uniform anisotropy and in the presence of both graded and stepped field has been studied. Also the same has been explored for a graded and stepped anisotropic system in presence of a uniform field. Finite size effect is analyzed for the variation of reversal time with gradient of field ($G_h$) and a scaling relation $〈\tau 〉\sim L^{-\beta }f\left(G_h{L}^{\alpha }\right)$ is proposed. Spatial variation of density profile for the projection states (i.e., +1, 0 and -1) has also been studied at the moment of reversal of magnetisation. The spatial variation of the number of spin flips per site is studied. Motion of the interface (or domain wall) with the gradient of field and gradient of anisotropy are investigated and are found to follow the hyperbolic tangent like behaviours in both cases. Since, both the anisotropy and the applied field have significant impact on the metastable lifetime, an interesting competitive scenario is observed for a graded anisotropic system in graded field and a stepped anisotropic system in stepped field. A line of marginal competition has been found out for both the cases separating the regions of field dominated reversal and anisotropy dominated reversal. The decay of the metastable volume fraction was found to follow the Avrami’s law. The mean reversal time was observed to decrease monotonically across the phase boundary of the ferro-para transition.

利用Metropolis单自旋翻转算法通过广泛的蒙特卡罗模拟研究了二维各向异性布鲁姆-卡佩尔铁磁体在磁场梯度变化和阶梯状变化影响下的亚稳态行为。从初始的完美有序状态开始，已经研究了磁场存在下的磁化反转。已经研究了具有均匀各向异性并且存在梯度场和阶梯场的系统的亚稳态寿命或磁化反转时间。对于均匀场存在的梯度和阶梯各向异性系统，也进行了同样的研究。分析了有限尺寸效应的反向时间随场梯度的变化（$G_H$）和比例关系 $〈\tau 〉〜{\mathrm{大号}}^{-\beta }F（G_H{\mathrm{大号}}^{\alpha }）$被提议。在磁化强度反转的时刻，还研究了投影状态（即+1、0和-1）的密度分布的空间变化。研究了每个位置的自旋翻转数的空间变化。研究了界面（或畴壁）随场梯度和各向异性梯度的运动，发现在两种情况下都遵循双曲线正切行为。由于各向异性和外加电场都对亚稳态寿命产生重大影响，因此对于梯度场中的梯度各向异性系统和阶梯场中的阶梯各向异性系统，观察到了有趣的竞争情况。对于将以场为主的反转区域和以各向异性为主导的反转区域分开的两种情况，都发现了一条边际竞争线。发现亚稳态体积分数的衰减遵循阿夫拉米定律。观察到平均逆转时间跨铁-对位转变的相界单调减少。