Designing two-dimensional ferroelectric materials from phosphorus-analogue structures

Two-dimensional (2D) ferroelectric (FE) materials with relatively low switching barrier and large polarization are promising candidates for next-generation miniaturized nonvolatile memory devices. Herein, we screen out 39 new 2D ferroelectric materials, MX (M: Group III-V elements; X: Group V-VII elements), in three phosphorus-analogue phases including black phosphorene-like alpha-phase, blue phosphorus-like beta-phase, and GeSe-like gamma-phase using high-throughput calculations. Seven materials (alpha-SbP, gamma-AsP, etc.) exhibit FE switching barriers lower than 0.3 eV/f.u., ferroelectric polarization larger than 2 x 10(-10) C/m, and high thermodynamic stability with energy above hull smaller than 0.2 eV/atom. We find that the larger the electronegativity difference between M and X, the larger the ferroelectric polarization. Moreover, larger electronegativity differences result in lower in-plane piezoelectric stress tensor (e(11)) for MX consisting of Group IV and VI elements and larger e(11) for those consisting of Group V elements. Further calculations predict a giant tunneling electroresistance in ferroelectric tunnel junction alpha-Sb(Sn)P/alpha-SbP/alpha-Sb(Te)P (1.26 x 10(4)%) and large piezoelectric strain coefficient in alpha-SnTe (396 pm/V), providing great opportunities to the design of non-volatile resistive memories, and high-performance piezoelectric devices.

Automated summary

Through high-throughput calculations, we have identified 39 two-dimensional ferroelectric materials with low switching barriers and large polarization. These materials include alpha, beta, and gamma phases. Seven of them exhibit ferroelectric switching barriers below 0.3 eV/f.u., polarization larger than 2 x 10(-10) C/m, and high thermodynamic stability. We have also found that larger electronegativity differences result in larger ferroelectric polarization.