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arXiv · 1604.00724

Robust Ferroelectricity in Monolayer Group-IV Monochalcogenides

Ruixiang Fei·Wei Kang·Li Yang
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Abstract

Ferroelectricity usually fades away when materials are thinned down below a critical value. Employing the first-principles density functional theory and modern theory of polarization, we show that the unique ionic-potential anharmonicity can induce spontaneous in-plane electrical polarizations and ferroelectricity in monolayer group-IV monochalcogenides MX (M=Ge, Sn; X=S, Se). Using Monte Carlo simulations with an effective Hamiltonian extracted from the parameterized energy space, we show these materials exhibit a two-dimensional ferroelectric phase transition that is described by fourth-order Landau theory. We also show the ferroelectricity in these materials is robust and the corresponding Curie temperature is higher than room temperature, making these materials promising for realizing ultra-thin ferroelectric devices of broad interest.

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Ruixiang Fei, Wei Kang, Li Yang. 2016-04-04. Robust Ferroelectricity in Monolayer Group-IV Monochalcogenides. https://doi.org/10.1103/physrevlett.117.097601

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