The TA - states can be represented by their cluster - size distribution that form the basis of kinetic theory of nucleation , and the shortening of the ACT time upon a stimulus pulse may be described by their evolution . On the microscopic scale , the TA - states may be described by their degree of medium - range order in the disordered - network structure that fl uctuates locally and temporally upon excitations . Numerical computations [ 14][15][16 ] based on the kinetic theory of nucleation have shown that , in response to a temperature change , the cluster population of the melt - quenched amorphous phase n am evolves gradually to the steady - state distribution n ss at an elevated temperature in a fi nite amount of time . [ 17 ] This time dependence is a consequence of the thermally - activated process during the growth of Phase - change ( PC ) materials have broad applications in rewritable DVD disks , [ 1 ] non - volatile electronic memories , [ 2 ] reconfi gurable electronics , [ 3 ] and more recently , in the area of neuromorphic computing [ 4][5][6][7 ] by virtue of their accumulative nature of the amorphous - to - crystalline phase transition ( ACT ) in PC materials , which allows biological - like read / write operations . PC memory ( PCM ) devices utilize both fast phase transitions between the amorphous ( a- ) and crystalline ( c- ) states of PC materials , and accompanying large electrical - resistance contrast , offering feasible intriguing applications in fast / nonvolatile / nanoscale built - in information storage , particularly for their ability to scale down to nanometer length scales . [ 8][9][10][11][12][13 ] However , the overall operation speeds of PCM devices , along with their corresponding power consumption , are intrinsically limited , in particular , owing to the ACT being much slower than the amorphization process . Moreover , much still remains to be done due to the contradictory nature of increasing the ACT speed while at the same time extending the amorphousstate data - retention properties of PC materials .