arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1105.3983cond-mat.stat-mechcond-mat.mes-hallcond-mat.soft
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畴壁取向有序性的微观研究

Microscopic approach to orientational order of domain walls

Daniel G. Barci, Daniel A. Stariolo

摘要:

我们开发了一个完全微观的,统计力学的方法来研究在不同尺度上的竞争相互作用的伊辛系统的相变。我们的目标是考虑在一个统一的框架取向和位置的序参量。在这项工作中,我们考虑二维条纹形成系统,其中,近晶,近晶和晶体相是可能的。我们在晶格中引入了一个有序序参量来度量界面的取向有序性。我们开发了一个平均场的方法,导致自由能,这是一个功能的磁化(密度)和取向(取向)序参量。对于一个特殊的系统,偶极阻挫伊辛铁磁体的序参量的自洽方程得到和描述的解决方案。我们表明,该系统在低温下的正方形晶格中,位置顺序(交错磁化)为零的伊辛-伊辛相。在较低的温度下,可以出现晶体条纹相。在连续极限中,本方法连接到金斯伯格-朗道理论,该理论具有连续对称性破缺的各向同性-非对称性相变。

英文摘要:

We develop a fully microscopic, statistical mechanics approach to study phase transitions in Ising systems with competing interactions at different scales. Our aim is to consider orientational and positional order parameters in a unified framework. In this work we consider two dimensional stripe forming systems, where nematic, smectic and crystal phases are possible. We introduce a nematic order parameter in a lattice, which measures orientational order of interfaces. We develop a mean field approach which leads to a free energy which is a function of both the magnetization (density) and the orientational (nematic) order parameters. Self-consistent equations for the order parameters are obtained and the solutions are described for a particular system, the Dipolar Frustrated Ising Ferromagnet. We show that this system has an Ising-nematic phase at low temperatures in the square lattice, where positional order (staggered magnetization) is zero. At lower temperatures a crystal-stripe phase may appear. In the continuum limit the present approach connects to a Ginsburg-Landau theory, which has an isotropic-nematic phase transition with breaking of a continuous symmetry.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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