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Electrically controlled valley polarization in 2D buckled honeycomb structures
Modern Physics Letters B ( IF 1.9 ) Pub Date : 2021-08-03 , DOI: 10.1142/s0217984921503905
Yu Sun 1 , Zi-Lin Yuan 1 , Qian-Ze Li 2 , Cai-Xin Zhang 1 , Ke-Qiu Chen 1 , Li-Ming Tang 1
Affiliation  

Generating and manipulating valley polarization in a controlled method is significant. The inherently broken centrosymmetry of the buckled honeycomb structures gives it both ferroelectricity and valley degree of freedom, which provides an opportunity to realize electrically controlled valley polarization. In the first step, we explored the origin of buckling. The hexagonal structure is polar due to buckling of the surface, but the degree of buckling and the energy barrier to switching electric polarization are determined not solely by the chemical composition. We combined the electronegativity difference, bond length and the distribution of charge density to describe quantificationally the polarity of chemical bonds. It shows the characteristics of relatively long bond-length but relatively small electronegativity-difference. For exploring the ferroelectricity of buckling structures and the behavior of ferroelectric (FE) control of the valley degree of freedom, the β-GaP is used as a model system to elucidate the strain effect on FE behavior and the magnetic proximity effect on the polarization and switching of valley. We found that the spontaneous polarization is positively correlated with the electronegativity difference within a certain range, and the compression strain can effectively manipulate spontaneous polarization and switch barrier. A combination of the magnetic proximity effect and the inversion of electric polarization can generate and switch valley polarization effectively.

中文翻译:

二维弯曲蜂窝结构中的电控谷极化

以受控方法生成和操纵谷极化非常重要。屈曲蜂窝结构固有的破坏中心对称性使其具有铁电性和谷自由度,这为实现电控谷极化提供了机会。第一步,我们探索了屈曲的起源。由于表面的屈曲,六边形结构是极性的,但屈曲程度和切换电极化的能垒不仅取决于化学成分。我们结合电负性差异、键长和电荷密度分布来定量描述化学键的极性。它具有键长较长但电负性差较小的特点。β-GaP被用作模型系统来阐明应变对FE行为的影响以及磁邻近效应对谷的极化和切换的影响。我们发现自发极化在一定范围内与电负性差异呈正相关,压缩应变可以有效地操纵自发极化和开关势垒。磁邻近效应和电极化反转的结合可以有效地产生和转换谷极化。
更新日期:2021-08-03
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