Quasicoherent nucleation mode in two-phase nanomagnets
Quasicoherent nucleation mode in two-phase nanomagnets
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DOI：
10.1103/physrevb.60.7359
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发表时间：
1999-09
影响因子：
3.7
通讯作者：
R. Skomski;J. Liu;D. Sellmyer
中科院分区：
文献类型：
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作者：
R. Skomski;J. Liu;D. Sellmyer
研究了先进磁性纳米结构的磁化过程。对于球形软或半硬晶粒的情况下，由一个非常硬的基体包围的鼓形核模式被发现。膨胀模具有相干模的径向角对称性，但由于其径向变化，它是非相干的。的径向依赖的膨胀模式是通过求解一个球形贝塞尔方程，这是受到适当的边界条件。与相干模式相反，膨胀模式产生取决于交换刚度和晶粒尺寸的成核场极化率。存在一个临界晶粒半径7.869 A / m 0 M s 2，超过此半径时，鼓包模式被修正的艾德卷曲模式所取代。在纳米结构中实现的成核模式会影响解释磁性样品外部形状所需的退磁场校正。由于强，但短程交换和弱，但长程静磁相互作用的纳米结构的长度尺度上的竞争，样品形状的磁滞回线的依赖性不能映射到一个纯粹的静磁退磁因子。@S0163 -1829 ~ 99！01734- 8#
Magnetization processes in advanced magnetic nanostructures are investigated. For the case of spherical soft or semihard grains surrounded by a very hard matrix a bulging nucleation mode is discovered. The bulging mode exhibits the radial angular symmetry of the coherent mode, but it is incoherent due to its radial variation. The radial dependence of the bulging mode is obtained by solving a spherical Bessel equation which is subject to appropriate boundary conditions. In contrast to the coherent mode, the bulging mode yields a nucleation-field coercivity which depends on the exchange stiffness and on the size of the grain. There is a critical grain radius 7.869 A A / m 0 M s 2 above which the bulging mode is replaced by a modified curling mode. The nucleation modes realized in nanostructures affect the demagnetizing-field corrections necessary to account for the external shape of magnetic samples. Since strong but short-range exchange and weak but long-range magnetostatic interactions compete on nanostructural length scales, the sample-shape dependence of the hysteresis loops cannot be mapped onto a purely magnetostatic demagnetizing factor. @ S0163-1829 ~ 99 ! 01734-8 #