The two-dimensional ferroelectric material GaTeCl monolayer*

Searching for new ferroelectric atomic-thick materials is an important issue in the condensed matter physics. Through first-principles investigation we proposed a new two-dimensional ferroelectric material GaTeCl monolayer which can be exfoliated from pre-existing GaTeCl bulk. The calculated in-plane ferroelectric polarization reaches 578 pC/m. The energy barriers per formula unit of the ferroelastic 90-degrees rotational and ferroelectric reversal transitions are 476 meV and 754 meV respectively. A tensile stress of 4.7 N/m perpendicular to the polarization can drive the polarization to rotate by 90 degrees. The second harmonic generation susceptibility calculations reveal that the GaTeCl monolayer has giant optical second harmonic generation with the intensity being strongly anisotropic. These ensure the great potential of GaTeCl monolayer in high-performance multi-functional applications.