Photostrictive Two-Dimensional Materials in the Monochalcogenide Family

• Published in: Physical review letters 2017-05, Vol.118 (22), p.227401-227401, Article 227401
• Main Authors: Haleoot, Raad, Paillard, Charles, Kaloni, Thaneshwor P, Mehboudi, Mehrshad, Xu, Bin, Bellaiche, L, Barraza-Lopez, Salvador
• Format: Article
• Language: English
• Subjects: Condensed Matter; Physics
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/physrevlett.118.227401

Photostriction is predicted for group-IV monochalcogenide monolayers, two-dimensional ferroelectrics with rectangular unit cells (the lattice vector a_{1} is larger than a_{2}) and an intrinsic dipole moment parallel to a_{1}. Photostriction is found to be related to the structural change induced by a screened electric polarization (i.e., a converse piezoelectric effect) in photoexcited electronic states with either p_{x} or p_{y} (in-plane) orbital symmetry that leads to a compression of a_{1} and a comparatively smaller increase of a_{2} for a reduced unit cell area. The structural change documented here is 10 times larger than that observed in BiFeO_{3}, making monochalcogenide monolayers an ultimate platform for this effect. This structural modification should be observable under experimentally feasible densities of photexcited carriers on samples that have been grown already, having a potential usefulness for light-induced, remote mechano-optoelectronic applications.