Despite its simple chemical constitution and unparalleled technological importance, the phase-change material germanium telluride (GeTe) still poses fundamental questions. In particular, the bonding mechanisms in amorphous GeTe have remained elusive to date, owing to the lack of suitable bond-analysis tools. Herein, we introduce a bonding indicator for amorphous structures, dubbed "bond-weighted distribution function" (BWDF), and we apply this method to amorphous GeTe. The results underline a peculiar role of homopolar Ge-Ge bonds, which locally stabilize tetrahedral fragments but not the global network. This atom-resolved (i.e., chemical) perspective has implications for the stability of amorphous "zero bits" and thus for the technologically relevant resistance-drift phenomenon.
Keywords: bond theory; crystal orbital overlap populations; molecular dynamics; phase-change materials; resistance drift.
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