Elasticity of 2D ferroelectrics across their paraelectric phase transformation

Abstract

The mechanical behavior of two-dimensional (2D) materials across 2D phase changes is unknown, and the finite temperature ($T$) elasticity of paradigmatic SnSe monolayers -- ferroelectric 2D materials turning paraelectric as their unit cell (u.c.) turns from a rectangle onto a square -- is described here in a progressive manner. To begin with, their zero$-T$ {\em elastic energy landscape} gives way to (Boltzmann-like) averages from which the elastic behavior is determined. These estimates are complemented with results from the strain-fluctuation method, which employs the energy landscape or {\em ab initio} molecular dynamics (MD) data. Both approaches capture the coalescence of elastic moduli $⟨C_{11}(T)⟩=⟨C_{22}(T)⟩$ due to the structural transformation. The broad evolution and sudden changes of elastic parameters $⟨C_{11}(T)⟩$, $⟨C_{22}(T)⟩$, and $⟨C_{12}(T)⟩$ of these atomically-thin phase-change membranes establishes a heretofore overlooked connection among 2D materials and soft matter.

arXiv comment5 pages, 4 figures. Originally submitted on January 11, 2022

References in corpus (23)

• The SIESTA method for ab initio order-N materials simulation
• Efficient index handling of multidimensional periodic boundary conditions
• Van der Waals heterostructures
• Valley polarization in MoS2 monolayers by optical pumping
• Efficient implementation of a van der Waals density functional: Application to double-wall carbon nanotubes
• Giant Piezoelectricity in Monolayer Group IV Monochalcogenides: SnSe, SnS, GeSe and GeS
• Purely in-plane ferroelectricity in monolayer SnS at room temperature
• Microscopic manipulation of ferroelectric domains in SnSe monolayers at room temperature
• Multiferroic Two-Dimensional Materials
• Enhanced piezoelectricity and modified dielectric screening of 2-D group-IV monochalcogenides
• Polarization and valley switching in monolayer group-IV monochalcogenides
• Colloquium: Physical properties of group-IV monochalcogenide monolayers
• Structural phase transition and material properties of few-layer monochalcogenides
• Disorder-assisted melting and the glass transition in amorphous solids
• Two-dimensional disorder in black phosphorus and monochalcogenide monolayers
• Tuning the ferro- to para-electric transition temperature and dipole orientation of group-IV monochalcogenide monolayers
• Topology of atomically thin soft ferroelectric membranes at finite temperature
• Thermoelectricity of Tin Selenide Monolayers Across a Structural Phase Transition
• Group-IV monochalcogenide monolayers: two-dimensional ferroelectrics with weak intra-layer bonds and a phosphorene-like monolayer dissociation energy
• Nonaffine lattice dynamics with the Ewald method reveals strongly nonaffine elasticity of α-quartz
• Quantum paraelastic two-dimensional materials
• Evolution of elastic moduli through a two-dimensional structural transformation
• Anomalous thermal expansion in Ising-like puckered sheets

Cited by in corpus (1)

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