AI 中文总结
研究铁电铋单层微观开关机制，用第一性原理等方法识别极化旋转路径，其能垒低且驱动自旋拓扑转变，单轴应变可调控，确立极化旋转为开关机制及二维铁电体可编程拓扑的有效途径。
AI 中文摘要
铋单层是首个二维元素铁电体，是将极性序与自旋轨道驱动拓扑耦合的有吸引力的平台。但其微观开关机制仍不清楚。本文利用第一性原理晶格动力学和对称适应模式分析，识别出平面内极化切换的一个先前被忽视的旋转路径。其能垒比直接反转低四倍多，自然地解释了分子动力学模拟中观察到的涡旋状畴纹理。值得注意的是，这种极化旋转还驱动自旋拓扑转变，使自旋陈数从\(C_s = -2\)变为\(0\)。定向单轴应变进一步控制极化方向并调节相关拓扑转变。这些结果确立了极化旋转作为铁电铋单层的开关机制以及二维铁电体中电和机械可编程拓扑的有效途径。
英文摘要
Bismuth monolayer is the first two-dimensional elemental ferroelectric and an appealing platform for coupling polar order to spin-orbit-driven topology. However, its microscopic switching mechanism remains elusive. Here, using first-principles lattice dynamics and symmetry-adapted mode analysis, we identify a previously overlooked rotational pathway for in-plane polarization switching. Its energy barrier is more than four times lower than that of direct reversal, naturally explaining the vortexlike domain textures observed in molecular dynamics simulations. Remarkably, this polarization rotation also drives a spin-topological transition, changing the spin Chern number from $C_s=-2$ to $0$. Directional uniaxial strain further steers the polarization orientation and tunes the associated topological transition. These results establish polarization rotation as the switching mechanism of ferroelectric Bi monolayer and as an efficient route to electrically and mechanically programmable topology in two-dimensional ferroelectrics.
Comments7 pages, 4 figures
