arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1210.5563cond-mat.mtrl-sciphysics.comp-ph
收藏

Cr2O3(0001)表面结构相变的微观起源

Microscopic origin of the structural phase transitions at the Cr2O3 (0001) surface

A. L. Wysocki, Siqi Shi, K. D. Belashchenko

摘要:

在Cr衬底上外延生长的Cr2O3(0001)薄膜表面经历了一系列不寻常的结构相变。为了了解潜在的微观机制,Cr2O3(0001)表面的结构和磁性在这里使用第一性原理电子结构计算进行了研究。两个竞争的表面铬网站被确定。的表面的能量描述的配置哈密顿参数确定使用总能量计算几个表面超晶胞。此外,还讨论了外延应变和磁有序对组态相互作用的影响。用蒙特卡罗模拟研究了系统的热力学。在零应变下,表面在165 K下经历有序相变。拉伸外延应变与反铁磁有序驱动系统走向强大的配置挫折,建议在较低的温度下的无序相变的机制。

英文摘要:

The surface of a Cr2O3 (0001) film epitaxially grown on Cr undergoes an unusual reentrant sequence of structural phase transitions. In order to understand the underlying microscopic mechanisms, the structural and magnetic properties of the Cr2O3 (0001) surface are here studied using first-principles electronic structure calculations. Two competing surface Cr sites are identified. The energetics of the surface is described by a configurational Hamiltonian with parameters determined using total energy calculations for several surface supercells. Effects of epitaxial strain and magnetic ordering on configurational interaction are also included. The thermodynamics of the system is studied using Monte Carlo simulations. At zero strain the surface undergoes an ordering phase transition at 165 K. Tensile epitaxial strain together with antiferromagnetic ordering drive the system toward strong configurational frustration, suggesting the mechanism for the disordering phase transition at lower temperatures.

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。

↑