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Room‐Temperature Ferroelectricity in Hexagonally Layered α‐In 2 Se 3 Nanoflakes down to the Monolayer Limit

2018; Wiley; Volume: 28; Issue: 50 Linguagem: Inglês

10.1002/adfm.201803738

1616-3028

Fei Xue, Weijin Hu, Ko‐Chun Lee, Li‐Syuan Lu, Junwei Zhang, Hao‐Ling Tang, Ali Han, Wei‐Ting Hsu, Shaobo Tu, Wen‐Hao Chang, Chenhsin Lien, Jr‐Hau He, Zhidong Zhang, Lain‐Jong Li, Xixiang Zhang,

Perovskite Materials and Applications

Abstract 2D ferroelectric material has emerged as an attractive building block for high‐density data storage nanodevices. Although monolayer van der Waals ferroelectrics have been theoretically predicted, a key experimental breakthrough for such calculations is still not realized. Here, hexagonally stacking α‐In 2 Se 3 nanoflake, a rarely studied van der Waals polymorph, is reported to exhibit out‐of‐plane (OOP) and in‐plane (IP) ferroelectricity at room temperature. Ferroelectric multidomain states in a hexagonal α‐In 2 Se 3 nanoflake with uniform thickness can survive to 6 nm. Most strikingly, the electric‐field‐induced polarization switching and hysteresis loop are, respectively, observed down to the bilayer and monolayer (≈1.2 nm) thicknesses, which designates it as the thinnest layered ferroelectric and verifies the corresponding theoretical calculation. In addition, two types of ferroelectric nanodevices employing the OOP and IP polarizations in 2H α‐In 2 Se 3 are developed, which are applicable for nonvolatile memories and heterostructure‐based nanoelectronics/optoelectronics.