Jahn–Teller distortion induced two-dimensional ferroelasticity in Mn2CuO6 monolayers with antiferromagnetic ordering†

Abstract

Designing and tuning Jahn–Teller (JT) distortion of two-dimensional (2D) materials plays a crucial role in multifunctional device applications, where significant 2D ferroelasticity in the crystal can be achieved by collaborative interactions among the spin, orbital and lattice degrees of freedom. Based on first-principles calculations, we report a Mn₂CuO₆ monolayer, a structural analogue derived from birnessite (δ-MnO₂), as the material candidate for achieving JT distortion induced 2D ferroelasticity with antiferromagnetic (AFM) ordering. By performing electronic and magnetic property simulations as well as crystallographic symmetry analysis, we found that the ferroelastic (FE) deformation of the Mn₂CuO₆ monolayer is not only attributed to the structural phase transition, but also to JT distortion derived from the interplay among the electron spin, AFM ordering and crystal lattice, associated with metal–semiconductor and ferrimagnetic (FiM)–AFM transitions. The magnitude of FE strain in Mn₂CuO₆ monolayers is comparable with those of other typical 2D FE materials (e.g. 1T-MoS₂). The simulation of AFM–paramangnetic (PM) transition temperature (T_N ∼ 332 K) for 2D FE in Mn₂CuO₆ further reveals the robust orbital orderings and room-temperature stable ferroelasticity. In addition, the FE switching among the three orientational variants is accompanied by the transformations of AFM spin textures, and a low transition barrier indicates that magnetic-tunable 2D lattice deformation can be readily achievable under experimental conditions, paving the way for the development of 2D magnetostriction engineering for controllable electronic device applications.