Enhanced Spontaneous Polarization in Ultrathin SnTe Films with Layered Antipolar Structure
- Max-Planck Inst. of Microstructure Physics Weinberg, Halle (Germany); Tsinghua Univ., Beijing (China)
- Univ. of Arkansas, Fayetteville, AR (United States)
- Tsinghua Univ., Beijing (China)
- Max-Planck Inst. of Microstructure Physics Weinberg, Halle (Germany)
- Tsinghua Univ., Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)
- Tsinghua Univ., Beijing (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); RIKEN Center for Emergent Matter Science (CEMS) – Wako, Saitama (Japan)
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. Here, 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.
- Research Organization:
- Univ. of Arkansas, Fayetteville, AR (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); German Research Foundation (DFG); National Natural Science Foundation of China (NSFC); Ministry of Science and Technology of China
- Grant/Contract Number:
- SC0016139; 1812/2‐1; 51561145005; 2016YFA0301002
- OSTI ID:
- 1763381
- Alternate ID(s):
- OSTI ID: 1480547
- Journal Information:
- Advanced Materials, Vol. 31, Issue 3; ISSN 0935-9648
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Similar Records
Group-IV monochalcogenide monolayers: Two-dimensional ferroelectrics with weak intralayer bonds and a phosphorenelike monolayer dissociation energy
Stacking Fault Induced Symmetry Breaking in van der Waals Nanowires