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Metavalent Bonding in Layered Phase-Change Memory Materials.

Wei Zhang¹, Hangming Zhang¹, Suyang Sun¹

¹Center for Alloy Innovation and Design (CAID), State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China.

Advanced Science (Weinheim, Baden-Wurttemberg, Germany)

|March 30, 2023

Summary

This summary is machine-generated.

Metavalent bonding (MVB) in layered materials is clarified, revealing its presence across van der Waals gaps. Strain engineering tunes MVB, impacting dielectric properties for phase-change memory applications.

Keywords:

atomic imaging metavalent bonding optical properties phase-change materials van der Waals

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Area of Science:

Materials Science
Solid-State Physics
Chemistry

Background:

Metavalent bonding (MVB) is key in phase-change materials, driven by competing electron delocalization and localization.
Crystalline phase-change materials exhibit MVB due to aligned p orbitals, leading to high dielectric constants.

Purpose of the Study:

To investigate MVB development across van der Waals-like gaps in layered Sb2Te3 and Ge-Sb-Te alloys.
To identify defects influencing MVB and explore strain effects on dielectric properties.

Main Methods:

Atomic imaging experiments and ab initio simulations to identify defects.
Application of uniaxial strain to tailor MVB and analyze resulting property changes.

Main Results:

MVB was found to develop across van der Waals gaps, with reduced p orbital coupling.
A novel extended defect in trigonal Sb2Te3 thin films was identified, impacting structural and optical properties.
Uniaxial strain significantly altered the dielectric function and reflectivity by tuning MVB.

Conclusions:

MVB exists across van der Waals gaps in layered materials, influenced by reduced orbital coupling and defects.
Strain engineering offers a method to control MVB and optimize dielectric properties for applications.
Design strategies for utilizing the trigonal phase in phase-change memory are proposed.