Ab Initio Study of Ferroelectric Critical Size of SnTe Low-Dimensional Nanostructures
Ab Initio Study of Ferroelectric Critical Size of SnTe Low-Dimensional Nanostructures
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DOI：
10.3390/nano10040732
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发表时间：
2020-04-01
期刊：
影响因子：
5.3
通讯作者：
Kitamura, Takayuki
中科院分区：
文献类型：
--
作者：
Shimada, Takahiro;Minaguro, Koichiro;Kitamura, Takayuki
除了传统铁电钙钛矿氧化物中存在的几纳米的铁电临界厚度之外，最近在SnTe单层中发现了最终薄尺寸的铁电性。这一发现表明SnTe在进一步低维小型化过程中可以维持铁电性的可能性。在这里，我们研究了铁电临界尺寸的低维SnTe纳米结构，如纳米带（1D）和纳米片（0D）使用第一性原理密度泛函理论计算。我们证明，最小的（一个单位晶胞宽度）的SnTe纳米带可以维持铁电性，并没有铁电临界尺寸的SnTe纳米带。另一方面，SnTe纳米片形成极化涡旋，并在4x4晶胞的表面积以下（一侧约25埃）失去其环形铁电性。我们还揭示了SnTe低维纳米结构中临界尺寸存在或不存在的原子和电子机制。我们的研究结果提供了一个深入了解低维硫族化合物层状材料的本征铁电临界尺寸。
Beyond a ferroelectric critical thickness of several nanometers existed in conventional ferroelectric perovskite oxides, ferroelectricity in ultimately thin dimensions was recently discovered in SnTe monolayers. This discovery suggests the possibility that SnTe can sustain ferroelectricity during further low-dimensional miniaturization. Here, we investigate a ferroelectric critical size of low-dimensional SnTe nanostructures such as nanoribbons (1D) and nanoflakes (0D) using first-principle density-functional theory calculations. We demonstrate that the smallest (one-unit-cell width) SnTe nanoribbon can sustain ferroelectricity and there is no ferroelectric critical size in the SnTe nanoribbons. On the other hand, the SnTe nanoflakes form a vortex of polarization and lose their toroidal ferroelectricity below the surface area of 4 x 4 unit cells (about 25 angstrom on one side). We also reveal the atomic and electronic mechanism of the absence or presence of critical size in SnTe low-dimensional nanostructures. Our result provides an insight into intrinsic ferroelectric critical size for low-dimensional chalcogenide layered materials.