Terahertz optics-driven phase transition in two-dimensional multiferroics

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, beta-GeSe and alpha-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.

Automated summary

The study proposes using a terahertz laser to trigger ferroic order switching in two-dimensional multiferroics, enhancing data storage density and read/write speed without damage. Through first-principles calculations, optically induced electronic, phononic, and mechanical responses of two experimentally fabricated multiferroic materials were investigated, showing the effective manipulation of stability in different orientation variants via laser polarization direction. The ultrafast transition kinetics and avoidance of conventional nucleation-growth phase transition processes were also demonstrated.