Uncovering β-relaxations in amorphous phase-change materials.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Relaxation processes significantly influence amorphous material properties.
• Characterizing amorphous phase-change materials (PCMs) is challenging due to the lack of bulk samples.
• β-relaxations are key features in understanding material dynamics.

Purpose of the Study:

• To characterize β-relaxations in amorphous PCMs using powder mechanical spectroscopy.
• To differentiate PCMs from other amorphous materials based on their relaxation dynamics.
• To explore the link between β-relaxation and crystallization kinetics in PCMs.

Main Methods:

• Utilized powder mechanical spectroscopy on powder samples of amorphous PCMs.
• Analyzed excess wing signatures, characteristic of β-relaxations, below glass transition temperatures.
• Compared relaxation behavior of PCMs with amorphous chalcogenides and non-PCMs.

Main Results:

• Detected prominent excess wings, indicative of β-relaxations, in amorphous PCMs.
• Observed significantly smaller β-relaxations in amorphous chalcogenides lacking PCM characteristics.
• Found a substantial drop in β-relaxations when transitioning from PCMs to non-PCMs.

Conclusions:

• Amorphous PCMs represent a distinct class of covalent glasses with preserved local atomic motions below glass transitions.
• A correlation exists between β-relaxation dynamics and crystallization kinetics in PCMs.
• These findings have implications for enhancing phase-change memory functionalities.