A possible mechanism of ultrafast amorphization in phase-change memory   alloys: an ion slingshot from the crystalline to amorphous position
  We propose that the driving force of an ultrafast crystalline-to-amorphous transition in phase-change memory alloys are strained bonds existing in the (metastable) crystalline phase. For the prototypical example of GST, we demonstrate that upon breaking of long Ge-Te bond by photoexcitation Ge ion shot from an octahedral crystalline to a tetrahedral amorphous position by the uncompensated force of strained short bonds. Subsequent lattice relaxation stabilizes the tetrahedral surroundings of the Ge atoms and ensures the long-term stability of the optically induced phase. 
A. V. Kolobov (1 and 2), A. S. Mishchenko (3 and 4), P. Fons (1), S.M.   Yakubenya (4) and J. Tominaga (1) ((1) AIST, Tsukub...