Understanding amorphous phase-change materials from the viewpoint of Maxwell rigidity

TL;DR

This paper uses molecular dynamics simulations to analyze the mechanical constraints in amorphous phase-change materials, revealing distinct compositional regions with different rigidity properties that are crucial for their functionality in memory devices.

Contribution

It introduces a novel method for enumerating mechanical constraints in amorphous PCMs and maps their phase diagram based on rigidity, providing atomic-scale insights.

Findings

Identification of two compositional regions: flexible and stressed rigid phases.

The stressed rigid phase includes known PCMs.

A new method for analyzing mechanical constraints in amorphous materials.

Abstract

Phase-change materials (PCMs) are the subject of considerable interest because they have been recognized as potential active layers for next-generation non-volatile memory devices, known as Phase Change Random Access Memories (PRAMs). By analyzing First Principles Molecular Dynamics simulations we develop a new method for the enumeration of mechanical constraints in the amorphous phase and show that the phase diagram of the most popular system (Ge-Sb-Te) can be split into two compositional regions having a well-defined mechanical character: a Tellurium rich flexible phase, and a stressed rigid phase that encompasses the known PCMs. This sound atomic scale insight should open new avenues for the understanding of PCMs and other complex amorphous materials from the viewpoint of rigidity.