The altermagnetism can achieve spin-split bands in collinear symmetry-compensated antiferromagnets. Here, we predict altermagnetic order in Janus monolayer Cr2SO with eliminated inversion symmetry, which can realize the combination of piezoelectricity and altermagnetism in a two-dimensional material, namely 2D piezoelectric altermagnetism. It is found that Cr2SO is an altermagnetic semiconductor, and the spin-split bands of both valence and conduction bands are near the Fermi level. The Cr2SO has large out-of-plane piezoelectricity (∣d31∣=0.97 pm/V), which is highly desirable for ultrathin piezoelectric device application. Due to spin-valley locking, both spin and valley can be polarized by simply breaking the corresponding crystal symmetry with uniaxial strain. Our findings provide a platform to integrate spin, piezoelectricity and valley in a single material, which is useful for multi-functional device applications.
@article{arxiv.2306.04094,
title = {Piezoelectric altermagnetism and spin-valley polarization in Janus monolayer $\mathrm{Cr_2SO}$},
author = {San-Dong Guo and Xiao-Shu Guo and Kai Cheng and Ke Wang and Yee Sin Ang},
journal= {arXiv preprint arXiv:2306.04094},
year = {2023}
}