Ultrafast photoexcitation driven non-thermal amorphization of GeTe

In this work, we modeled the photoexcitation-driven non-thermal amorphization process in GeTe using nonadiabatic quantum molecular dynamics (NAQMD). Results show that the amorphization of crystalline GeTe occurs at a valence electron excitation threshold of 4%. The photoexcited-induced charge transfer as well as the evolution of excited electronic states is characterized in order to understand the amorphization process. The loss of long-range order of the crystalline structure without fulfilling the Lindemann criterion for melting is achieved by upsetting the Peierls distortion that stabilize the cubic structure of GeTe. That allows for electron-phonon coupling induced large local distortions of Ge-Te bonding leading to collapse of the fragile metavalently bonded crystalline structure. This work provides insights into electronic mechanisms of ultrafast non-thermal amorphization processes induced by intense femtosecond laser excitation of metavalently bonded materials.