Altermagnets have garnered great interest due to their non-relativistic spin splitting and novel physical properties. However, the control of altermagnetic states remains underexplored. Here, we propose a unique multiferroic state, i.e. ferroelastic altermagnetic state, in which ferroelastic strain couples directly to the spin-splitting. Through symmetry analysis and first-principles calculations, we identify the ferroelastic d-wave altermagnetism of puckered pentagonal CoSe2 monolayer. Interestingly, uniaxial stress can induce a ferroelastic phase transition, accompanied by a 90° rotation of the spin-splitting bands. Cooperative rotation of the lattice and N\'eel vectors preserves the sign of Kerr angle, whereas noncooperative rotation reverses it. Our work provides a general strategy for manipulating altermagnetism in multiferroic systems and opens other avenues for exploring emergent magnetoelastic phenomena.
@article{arxiv.2510.14193,
title = {Ferroelasticity tunable altermagnets},
author = {Ning Ding and Haoshen Ye and Shan-Shan Wang and Shuai Dong},
journal= {arXiv preprint arXiv:2510.14193},
year = {2025}
}