Enhanced Spontaneous Polarization in Ultrathin SnTe Films with Layered Antipolar Structure
| Autor: | Salvador Barraza-Lopez, Xi Chen, Shuai-Hua Ji, Haicheng Lin, Avanindra K. Pandeya, X. J. Hu, Kun Zhao, Qi-Kun Xue, Amilcar Bedoya-Pinto, Kai Chang, Thaneshwor P. Kaloni, Stuart S. P. Parkin, Yong Zhong, Ilya Kostanovskiy |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
Condensed matter physics Mechanical Engineering Transition temperature 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Ferroelectricity 0104 chemical sciences law.invention Tin telluride symbols.namesake chemistry.chemical_compound chemistry Mechanics of Materials law Monolayer symbols General Materials Science Orthorhombic crystal system van der Waals force Scanning tunneling microscope 0210 nano-technology Molecular beam epitaxy |
| Zdroj: | Advanced Materials Technologies Advanced Materials |
| ISSN: | 1521-4095 |
| Popis: | 2D SnTe films with a thickness of as little as 2 atomic layers (ALs) have recently been shown to be ferroelectric with in-plane polarization. Remarkably, they exhibit transition temperatures (Tc ) much higher than that of bulk SnTe. Here, combining molecular beam epitaxy, variable temperature scanning tunneling microscopy, and ab initio calculations, the underlying mechanism of the Tc enhancement is unveiled, which relies on the formation of γ-SnTe, a van der Waals orthorhombic phase with antipolar inter-layer coupling in few-AL thick SnTe films. In this phase, 4n - 2 AL (n = 1, 2, 3…) thick films are found to possess finite in-plane polarization (space group Pmn21), while 4n AL thick films have zero total polarization (space group Pnma). Above 8 AL, the γ-SnTe phase becomes metastable, and can convert irreversibly to the bulk rock salt phase as the temperature is increased. This finding unambiguously bridges experiments on ultrathin SnTe films with predictions of robust ferroelectricity in GeS-type monochalcogenide monolayers. The observed high transition temperature, together with the strong spin-orbit coupling and van der Waals structure, underlines the potential of atomically thin γ-SnTe films for the development of novel spontaneous polarization-based devices. |
| Databáze: | OpenAIRE |
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