Determination of the anisotropic elastic properties of rocksalt Ge2Sb2Te5 by XRD, residual stress and DFT

Abstract

The chalcogenide material Ge2Sb2Te5 is the prototype phase-change material, with widespread applications for optical media and random access memory. However, the full set of its independent elastic properties has not yet been published. In this study, we determine the elastic constants of the rocksalt Ge2Sb2Te5, experimentally by x-ray diffraction (XRD) and residual stress, and computationally by density functional theory (DFT). The stiffnesses (XRD-stress/DFT) in GPa are C11 = 41/58, C12 = 7/8 and C44 = 8/12 and the Zener ratio is 0.46/0.48. These values are important to understand the effect of elastic distortions and non-melting processes on the performances of increasingly small phase change data bits.