科研之友
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摘要
Ultrafast photoexcitation can decouple the multilevelnonequilibriumdynamics of electron-lattice interactions, providing an idealprobe for dissecting photoinduced phase transition in solids. Here,real-time time-dependent density functional theory simulations combinedwith occupation-constrained DFT methods are employed to explore thenonadiabatic paths of optically excited a-GeTe. Resultsshow that the short-wavelength ultrafast laser is capable of generatingfull-domain carrier excitation and repopulation, whereas the long-wavelengthultrafast laser favors the excitation of lone pair electrons in theantibonded state. Photodoping makes the double-valley potential energysurface shallower and allows the insertion of A(1g ) coherent forces in the atomic pairs, by which the phase reversalof Ge and Te atoms in the & LeftAngleBracket;001 & RightAngleBracket; direction is activatedwith ultrafast suppression of the Peierls distortion. These findingshave far-reaching implications regarding nonequilibrium phase engineeringstrategies based on phase-change materials.
