Vanishing‐Harmonicity and Phase‐Change Materials

Phase-change material (PCMs) store data using the contrast (electrical or optical) between two phases: a conductive crystalline phase and weakly amorphous phase. Most PCMs have distorted octahedral structure. The comes mainly from electronic In PCMs, spontaneous symmetry breaking mechanism, Peierls distortion, transforms metallic structure into lower-density semiconducting simple tight-binding model of covalent bond, parameters that control this characterized by parameter η, are analyzed. effective interatomic potential E(η) is developed in Landau-type series η: = E0 + E2η2 E4η4. with largest those for which has disappearing harmonic contribution ( E 2 0 ) vanishing gap. This called as an “incipient distortion.” It coincides so-called metal”. hardness repulsive number electrons per atom play important role. vibrational properties anomalous Grüneisen parameter, specific to also studied.