正交结构铋单层中局域场和偶极-偶极相互作用对偶极矩自发有序化的影响
Effect of the local field and dipole-dipole interaction on the spontaneous ordering of dipole moments in bismuth monolayers with an orthorhombic structure
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中文总结 AI 辅助
研究正交结构铋单层中偶极矩自发有序化，用两种互补方法，一是通过铋原子极化率和局域场确定晶格位点偶极矩，二是分析振动光谱，揭示了不同相及相关关系。
中文摘要 AI 辅助
采用两种互补方法，研究了正交结构铋单层相对于晶格位点自发电偶极矩出现的不稳定性。第一种方法通过铋原子极化率确定晶格位点偶极矩并考虑局域洛伦兹-洛伦茨场，表明正交铋单层可能存在多个反铁电和铁电相。第二种方法分析了非极性对称晶格的振动光谱，揭示了对应单层铁电和反铁电不稳定性的两种软光学模式。还展示了铁电相中玻恩有效电荷与极化方向的关系及其在降低极性光学声子频率中的作用。
英文摘要
Using two complementary approaches, the instability of bismuth monolayers with an orthorhombic structure with respect to the emergence of spontaneous electric dipole moments at the crystal lattice sites has been studied. The first approach, based on determining the dipole moments of lattice sites through the polarizability of bismuth atoms and taking into account the local Lorentz-Lorenz field, suggests the possibility of the existence of several antiferroelectric and ferroelectric phases in orthorhombic bismuth monolayers. Using the second approach, the vibrational spectrum of a nonpolar symmetric lattice has been analyzed, and two types of soft optical modes corresponding to the ferroelectric and antiferroelectric instabilities of the monolayers have been revealed. The relationship of the Born effective charges to the polarization direction in the ferroelectric phase, as well as their role in the reduction of the frequency of the polar optical phonon, which characterizes the lattice deformation in the ferroelectric phase due to the dipole-dipole interaction, has been shown.
