| Summary: | We investigate the critical size of ferroelectricity in monolayer tin telluride (SnTe) nanoribbon by using ab initio (first-principles) density functional theory calculations. The edge of SnTe nanoribbon tends to suppress the ferroelectricity and the edge effect ranges within the 4 unit cells (~1.8 nm) from the edge. In nanoribbons, ferroelectric polarizations decrease monotonically with decreasing nanoribbon width. Ferroelectricity finally disappears in nanoribbons with 4 unit-cell width or less. This signifies that the ferroelectric critical size of SnTe nanoribbon is 4 unit cells (1.8 nm) due to the edge effect. However, the ferroelectricity of nanoribbon below the critical width is restored under uniaxial tensile strain along the [100] direction. Thus, the critical width of ferroelectric disappearance can be eliminated by tensile strain. Our results indicate that the lattice width ferroelectric material can be mechanically realized by tensile strain.
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