Flexoelectricity in atomic monolayers from first principles

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid State Chemistry

Background:

• The flexoelectric effect, a coupling between strain and polarization, is crucial for understanding electromechanical phenomena in dielectric materials.
• Atomic monolayers offer unique platforms for exploring fundamental material properties due to their reduced dimensionality.

Purpose of the Study:

• To investigate the flexoelectric effect in a diverse range of 54 atomic monolayers.
• To calculate transversal flexoelectric coefficients and identify their electronic origins.
• To establish structure-property relationships for flexoelectricity in low-dimensional materials.

Main Methods:

• Utilized ab initio Density Functional Theory (DFT) simulations.
• Performed symmetry-adapted DFT calculations for accurate flexoelectric coefficient determination.
• Analyzed various material classes including Group III monochalcogenides, TMDs, TMTs, and others.

Main Results:

• Observed linear flexoelectric behavior across all studied monolayers.
• Found comparable flexoelectric coefficients along principal bending directions.
• Identified transition metal trichalcogenides (TMTs) with coefficients up to five times larger than graphene.
• Determined that flexoelectricity scales with monolayer thickness, elastic modulus, and atomic polarizability.

Conclusions:

• The flexoelectric effect in atomic monolayers is strongly influenced by material composition and structure.
• TMTs represent promising candidates for applications leveraging strong flexoelectric responses.
• Understanding the electronic origins provides a pathway for designing novel flexoelectric materials.