Realization of semiconducting layered multiferroic heterojunctions via asymmetrical magnetoelectric coupling
Baishun Yang, Bin Shao, Jianfeng Wang, Yang Li, ChiYung Yam, Shengbai Zhang, Bing Huang
Abstract
Two-dimensional (2D) semiconducting multiferroics that can effectively couple magnetic and polarization $(P)$ orders have great interest for both fundamental research and technological applications in nanoscale, which are, however, rare in nature. In this paper, we propose a general mechanism to realize semiconducting 2D multiferroics via van der Waals (vdW) heterojunction engineering, as demonstrated in a typical heterostructure consisting of magnetic bilayer $\mathrm{Cr}{\mathrm{I}}_{3}(bi\text{-Cr}{\mathrm{I}}_{3})$ and ferroelectric monolayer ${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$. Interestingly, the novel indirect orbital coupling between $\mathrm{Se}\phantom{\rule{0.28em}{0ex}}4p$ and $\mathrm{Cr}\phantom{\rule{0.28em}{0ex}}3d$ orbitals, intermediated by the interfacial $\mathrm{I}\phantom{\rule{0.28em}{0ex}}5p$ orbitals, is switchable in the opposite $P$ configurations, resulting in an unexpected mechanism of strong asymmetrical magnetoelectric coupling. Therefore, along with the noticeable ferroelectric energy barrier induced by ${\mathrm{In}}_{2}{\mathrm{Se}}_{3}$, the realization of opposite magnetic orders in opposite $P$ configurations can eventually result in the novel multiferroicity in $bi\text{\ensuremath{-}}{\mathrm{CrI}}_{3}/{\mathrm{In}}_{2}{\mathrm{Se}}_{3}$. Finally, we demonstrate that our mechanism can generally be applied to design other vdW multiferroics even with tunable layer thickness.