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arXiv 2301.06282cond-mat.mes-hall
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电场下的轨道磁化与双层陈数系统的轨道磁电极化率

Orbital Magnetization under an Electric Field and Orbital Magnetoelectric Polarizabilty for a Bilayer Chern System

Si-Si Wang, Yi-Ming Dai, Hui-Hui Wang, Hao-Can Chen, Biao Zhang, Yan-Yang Zhang

AI总结:

本文通过双层陈数模型研究电场下轨道磁化的平均方式,证明只有整个样品平均才可靠,并据此分析轨道磁电极化率与贝里曲率响应的关系,提出增强材料OMP和CSOMP的方法。

摘要:

在无外电场陈绝缘体的轨道磁化(OM)实空间形式中,对体区域或整个样品进行局域轨道磁化平均都是正确的。然而,对于处于外电场中的层状陈绝缘体,这一情形与轨道磁电耦合的非平庸本质直接相关,边界在该形式中的作用仍然不明确。基于一个在半填充下陈数可调的双层模型,我们在非零垂直电场下数值研究了上述两种不同平均方式下的轨道磁化。结果表明,在这种情况下,非零陈数会导致体区域平均的轨道磁化产生规范平移,而整个样品平均的轨道磁化则不存在这种规范平移。这说明对于陈绝缘体,在非零电场下只有整个样品平均才能可靠地计算轨道磁化。在此基础上,我们研究了采用整个样品平均的轨道磁电极化率(OMP)和陈-西蒙斯轨道磁电极化率(CSOMP)。我们还给出了OMP(CSOMP)与贝里曲率对电场响应之间的关系。贝里曲率对电场的响应越强,OMP(CSOMP)就越强。除了澄清计算方法外,我们的结果还提供了一种增强材料OMP和CSOMP的有效方法。

英文摘要:

In the real space formalism of orbital magnetization (OM) for a Chern insulator without an external electric field, it is correct to average the local OM either over the bulk region or over the whole sample. However for a layered Chern insulator in an external electric field, which is directly related to the nontrivial nature of orbital magnetoelectric coupling, the role of boundaries remains ambiguous in this formalism. Based on a bilayer model with an adjustable Chern number at half filling, we numerically investigate the OM with the above two different average types under a nonzero perpendicular electric field. The result shows that in this case, the nonzero Chern number gives rise to a gauge shift of the OM with the bulk region average, while this gauge shift is absent for the OM with the whole sample average. This indicates that only the whole sample average is reliable to calculate the OM under a nonzero electric field for Chern insulators. On this basis, the orbital magnetoelectric polarizablity (OMP) and the Chern-Simons orbital magnetoelectric polarizablity (CSOMP) with the whole sample average are studied. We also present the relationship between the OMP (CSOMP) and the response of Berry curvature to the electric field. The stronger the response of Berry curvature to electric field, the stronger is the OMP (CSOMP). Besides clarify the calculation methods, our result also provides an effective method to enhance OMP and CSOMP of materials.

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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