Highly tunable β-relaxation enables the tailoring of crystallization in phase-change materials
Yudong Cheng, Qun Yang, Jiangjing Wang, Theodoros Dimitriadis, Mathias Schumacher, Huiru Zhang, Maximilian J. Müller, Narges Amini, Fan Yang, Alexander Schoekel, Julian Pries, Riccardo Mazzarello, Matthias Wuttig, Hai‐Bin Yu, Shuai Wei
Abstract
Abstract In glasses, secondary (β-) relaxations are the predominant source of atomic dynamics. Recently, they have been discovered in covalently bonded glasses, i.e., amorphous phase-change materials (PCMs). However, it is unclear what the mechanism of β-relaxations is in covalent systems and how they are related to crystallization behaviors of PCMs that are crucial properties for non-volatile memories and neuromorphic applications. Here we show direct evidence that crystallization is strongly linked to β-relaxations. We find that the β-relaxation in Ge 15 Sb 85 possesses a high tunability, which enables a manipulation of crystallization kinetics by an order of magnitude. In-situ synchrotron X-ray scattering, dielectric functions, and ab-initio calculations indicate that the weakened β-relaxation intensity stems from a local reinforcement of Peierls-like distortions, which increases the rigidity of the bonding network and decreases the dynamic heterogeneity. Our findings offer a conceptually new approach to tuning the crystallization of PCMs based on manipulating the β-relaxations.