Ultrafast Laser-Induced Phase Transitions in Amorphous GeSb Films

Abstract:

Time-resolved measurements of the spectral dielectric function reveal new information about ultrafast phase transitions induced by femtosecond laser pulses in Sb-rich amorphous GeSb films. The excitation generates a non-thermal phase within 200 fs. The dielectric function of this phase differs from that of the crystalline phase, contrary to previous suggestions of a disorder-to-order transition. The observed dielectric function is close to that of the liquid phase, indicating an ultrafast disorder-to-disorder transition from the amorphous phase to a glassy (liquid-like disordered) state.