Room-Temperature Ferroelectricity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>1</mml:mn><mml:msup><mml:mrow><mml:mi mathvariant="normal">T</mml:mi></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>ReS</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> Multilayers
Yi Wan, Ting Hu, Xiaoyu Mao, Jun Fu, Kai Yuan, Yu Song, Xuetao Gan, Xiaolong Xu, Mingzhu Xue, Xing Cheng, Chengxi Huang, Jinbo Yang, Lun Dai, Hualing Zeng, Erjun Kan
Abstract
van der Waals materials possess an innate layer degree of freedom and thus are excellent candidates for exploring emergent two-dimensional ferroelectricity induced by interlayer translation. However, despite being theoretically predicted, experimental realization of this type of ferroelectricity is scarce at the current stage. Here, we demonstrate robust sliding ferroelectricity in semiconducting $1{\mathrm{T}}^{\ensuremath{'}}\text{\ensuremath{-}}{\mathrm{ReS}}_{2}$ multilayers via a combined study of theory and experiment. Room-temperature vertical ferroelectricity is observed in two-dimensional $1{\mathrm{T}}^{\ensuremath{'}}\text{\ensuremath{-}}{\mathrm{ReS}}_{2}$ with layer number $N\ensuremath{\ge}2$. The electric polarization stems from the uncompensated charge transfer between layers and can be switched by interlayer sliding. For bilayer $1{\mathrm{T}}^{\ensuremath{'}}\text{\ensuremath{-}}{\mathrm{ReS}}_{2}$, the ferroelectric transition temperature is estimated to be $\ensuremath{\sim}405\text{ }\text{ }\mathrm{K}$ from the second harmonic generation measurements. Our results highlight the importance of interlayer engineering in the realization of atomic-scale ferroelectricity.