论文标题
由随机变化的磁场驱动的核心壳纳米颗粒中的非平衡多个过渡
Nonequilibrium Multiple Transitions in the Core-shell Ising Nanoparticles Driven by Randomly Varying Magnetic Fields
论文作者
论文摘要
通过蒙特卡洛模拟研究了核壳纳米颗粒的非平衡行为。核心包括$σ= 1/2 $的ising旋转，外壳包含$ s = 1 $的ising旋转。核心内部和外壳中的相互作用被认为是铁磁，但核心与壳之间的界面相互作用是抗铁磁磁性的。纳米颗粒系统保持在开放的边界条件下，并由随机变化（及时但在空间上均匀）的磁场驱动。根据随机变化场的宽度和系统的温度，核心，壳和总磁化强度的变化以使得时间平均而消失，以消失，因为随机场的宽度较高，表现出动态的对称性破坏过渡。敏感性在两个不同的温度下达到峰值，表明多个过渡。非平衡多个跃迁的相边界在由温度轴和随机变化场的宽度形成的平面中绘制。此外，已经讨论了核心和壳厚度对多个跃迁的影响。
The nonequilibrium behaviour of a core-shell nanoparticle has been studied by Monte- Carlo simulation. The core consists of Ising spins of $σ=1/2$ and the shell contains Ising spins of $S=1$. The interactions within the core and in the shell are considered ferromagnetic but the interfacial interaction between core and shell is antiferromagnetic. The nanoparticle system is kept in open boundary conditions and is driven by randomly varying (in time but uniform over the space) magnetic field. Depending on the width of the randomly varying field and the temperature of the system, the core, shell and total magnetization varies in such a manner that the time averages vanish for higher magnitude of the width of random field, exhibiting a dynamical symmetry breaking transitions. The susceptibilities get peaked at two different temperatures indicating nonequilibrium multiple transitions. The phase boundaries of the nonequilibrium multiple transitions are drawn in the plane formed by the axes of temperature and the width of the randomly varying field. Furthermore, the effects of the core and shell thicknesses on the multiple transitions have been discussed.
