Specific heat in two-dimensional melting.
Specific heat in two-dimensional melting.
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DOI：
10.1103/physrevlett.113.127801
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发表时间：
2013-12
影响因子：
8.6
通讯作者：
S. Deutschländer;A. Puertas;G. Maret;P. Keim
中科院分区：
文献类型：
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作者：
S. Deutschländer;A. Puertas;G. Maret;P. Keim
我们报道了二维微米级超顺磁性粒子熔化转变(S)附近的比热Cn，由位置和内能的涨落计算，并进行了相应的蒙特卡罗模拟。由于胶体系统提供了单粒子分辨率，它们为比较CN(T)峰位和对称性破缺的实验温度提供了独特的可能性。虽然序参数关联函数证实了Kosterlitz-Thouless-Halperin-Nelson-Young熔化情景，其中平移和取向的有序对称性在不同的温度下被破坏，中间存在所谓的六相，但我们在六相内观察到了单峰的比热，实验和模拟结果很好地吻合。因此，该峰值与破坏对称性无关，但可以用总缺陷密度来解释，总缺陷密度与孤立位错的最大增加相关。潜热的缺乏有力地支持了这两个相变的连续性。
We report the specific heat cN around the melting transition(s) of micrometer-sized superparamagnetic particles confined in two dimensions, calculated from fluctuations of positions and internal energy, and corresponding Monte Carlo simulations. Since colloidal systems provide single particle resolution, they offer the unique possibility to compare the experimental temperatures of the peak position of cN(T) and symmetry breaking, respectively. While order parameter correlation functions confirm the Kosterlitz-Thouless-Halperin-Nelson-Young melting scenario where translational and orientational order symmetries are broken at different temperatures with an intermediate so called hexatic phase, we observe a single peak of the specific heat within the hexatic phase, with excellent agreement between experiment and simulation. Thus, the peak is not associated with broken symmetries but can be explained with the total defect density, which correlates with the maximum increase of isolated dislocations. The absence of a latent heat strongly supports the continuous character of both transitions.