Displacive martensitic phase transition is potentially promising in semiconductor-based data storage applications with fast switching speed. In addition to traditional phase transition materials, the recently discovered two-dimensional ferroic materials are receiving a lot of attention owing to their fast ferroic switching dynamics, which could tremendously boost data storage density and enhance read/write speed. In this study, we propose that a terahertz laser with an intermediate intensity and selected frequency can trigger ferroic order switching in two-dimensional multiferroics, which is a damage-free noncontacting approach. Through first-principles calculations, we theoretically and computationally investigate optically induced electronic, phononic, and mechanical responses of two experimentally fabricated multiferroic (with both ferroelastic and ferroelectric) materials, β-GeSe and α-SnTe monolayer. We show that the relative stability of different orientation variants can be effectively manipulated via the polarization direction of the terahertz laser, which is selectively and strongly coupled with the transverse optical phonon modes. The transition from one orientation variant to another can be barrierless, indicating ultrafast transition kinetics and the conventional nucleation-growth phase transition process can be avoidable.

在基于半导体的数据存储应用中，具有快速切换速度的位移马氏体相变可能很有前途。除了传统的相变材料以外，最近发现的二维铁磁材料由于其快速的铁磁切换动力学特性而受到了广泛的关注，这可以极大地提高数据存储密度并提高读/写速度。在这项研究中，我们提出具有中等强度和选定频率的太赫兹激光器可以触发二维多铁性中的铁性有序切换，这是一种无损伤的非接触方法。通过第一性原理计算，我们在理论上和计算上研究了光感应电子，声子，β- GeSe和α- SnTe单层。我们表明，可以通过太赫兹激光的偏振方向有效地操纵不同取向变量的相对稳定性，该偏振方向与横向光学声子模式有选择地并强烈地耦合在一起。从一种取向变体到另一种取向变体的转变可以是无障碍的，这表明超快的转变动力学，并且可以避免常规的成核-生长相转变过程。