Wysin G M, Pereira A R, Moura-Melo W A, de Araujo C I L
Department of Physics, Kansas State University, Manhattan, KS 66506-2601, USA.
J Phys Condens Matter. 2015 Feb 25;27(7):076004. doi: 10.1088/0953-8984/27/7/076004. Epub 2015 Feb 2.
Thermodynamic properties of a spin ice model on a Kagomé lattice are obtained from dynamic simulations and compared with properties in square lattice spin ice. The model assumes three-component Heisenberg-like dipoles of an array of planar magnetic islands situated on a Kagomé lattice. Ising variables are avoided. The island dipoles interact via long-range dipolar interactions and are restricted in their motion due to local shape anisotropies. We define various order parameters and obtain them and thermodynamic properties from the dynamics of the system via a Langevin equation, solved by the Heun algorithm. Generally, a slow cooling from high to low temperature does not lead to a particular state of order, even for a set of coupling parameters that gives well thermalized states and dynamics. At very low temperature, however, square ice is more likely to reach states near the ground state than Kagomé ice, for the same island coupling parameters.
通过动态模拟获得了 Kagomé 晶格上自旋冰模型的热力学性质，并与方形晶格自旋冰的性质进行了比较。该模型假设位于 Kagomé 晶格上的平面磁岛阵列具有类似海森堡的三分量偶极子。避免使用伊辛变量。岛偶极子通过长程偶极相互作用相互作用，并且由于局部形状各向异性而限制其运动。我们定义了各种序参量，并通过由休恩算法求解的朗之万方程从系统动力学中获得它们和热力学性质。一般来说，即使对于一组能给出良好热化状态和动力学的耦合参数，从高温到低温的缓慢冷却也不会导致特定的有序状态。然而，在非常低的温度下，对于相同的岛耦合参数，方形冰比 Kagomé 冰更有可能达到接近基态的状态。
