Structure and melting behavior of classical bilayer crystals of dipoles
Structure and melting behavior of classical bilayer crystals of dipoles
复制标题
经典偶极子双层晶体的结构和熔化行为
DOI：
10.1103/physrevb.78.024108
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发表时间：
2008-07-01
影响因子：
3.7
通讯作者：
Pupillo, Guido
中科院分区：
文献类型：
--
作者：
Lu, Xin;Wu, Chang-Qin;Pupillo, Guido
我们研究了一个经典的双层偶极子系统的结构和熔化，在这种情况下，偶极子垂直于各层的平面取向，每层的偶极子密度相同。由于偶极-偶极相互作用的各向异性，我们发现基态构型是由两个相互重叠的六角形晶体给出的，与层间距和偶极密度无关。对于较大的层间距离，这些晶体是独立的，而在较小的层间距离的相反限制下，系统表现为成对偶极子的二维晶体。在声子激发的谐波近似下，这些晶体构型的熔化温度与层间距离呈非单调依赖关系，这与固定温度下固体-液体-固体-液体转变形式的重入熔化行为有关。
We study the structure and melting of a classical bilayer system of dipoles in a setup where the dipoles are oriented perpendicular to the planes of the layers and the density of dipoles is the same in each layer. Due to the anisotropic character of the dipole-dipole interactions, we find that the ground-state configuration is given by two hexagonal crystals positioned on top of each other, independent of the interlayer spacing and dipolar density. For large interlayer distances these crystals are independent, while in the opposite limit of small interlayer distances the system behaves as a two-dimensional crystal of paired dipoles. Within the harmonic approximation for the phonon excitations, the melting temperature of these crystalline configurations displays a nonmonotonic dependence on the interlayer distance, which is associated with a re-entrant melting behavior in the form of solid-liquid-solid-liquid transitions at fixed temperature.