论文标题
PEIERLS过渡，铁电和单旋风形成单层$ _2 $
Peierls transition, ferroelectricity, and spin-singlet formation in the monolayer VOI$_2$
论文作者
论文摘要
使用{\ it i ab intib}密度功能理论和单端哈伯德模型通过密度矩阵重质化组方法计算，我们系统地研究了单层voi $ _2 $，并具有$ 3D^1 $ electronic Conficturation。我们的声子计算表明，正交$ PMM2 $ Fe-II阶段是最有可能的基础状态，涉及沿$ a $ a-axis和$ b $轴沿$ a $ a轴和v-v二聚化的铁电失真。具体而言，由空V（$ d_ {xz/yz} $和$ d_ {3z^2-r^2} $）和o $ 2p $态之间的耦合引起的“伪jahn-teller”效应是稳定了从帕洛莱氏菌相位的机制。此外，半填充的金属$ d_ {xy} $ band沿$ b $轴显示了peierls的不稳定性，从而诱导了V-V二聚体化。我们还发现，由于基态近乎耦合的自旋单线形成，沿V-V链的较短距离抗铁磁耦合。
Using {\it ab initio} density functional theory and single-orbital Hubbard model calculations via the density matrix renormalization group method, we systematically studied the monolayer VOI$_2$ with a $3d^1$ electronic configuration. Our phonon calculations indicate that the orthorhombic $Pmm2$ FE-II phase is the most likely ground state, involving a ferroelectric distortion along the $a$-axis and V-V dimerization along the $b$-axis. Specifically, the "pseudo Jahn-Teller" effect caused by the coupling between empty V ($d_{xz/yz}$ and $d_{3z^2-r^2}$) and O $2p$ states is proposed as the mechanism that stabilizes the ferroelectric distortion from the paraelectric phase. Moreover, the half-filled metallic $d_{xy}$ band displays a Peierls instability along the $b$-axis, inducing a V-V dimerization. We also found very short-range antiferromagnetic coupling along the V-V chain due to the formation of nearly-decoupled spin singlets in the ground state.
