Large piezo/flexoelectric and flexomagnetic effect in semiconducting cobalt telluride monolayer

Abstract

Engineering piezo/flexoelectricity and flexomagnetism in two-dimensional (2D) materials beyond the best-known graphene and transition metal dichalcogenides holds potentials for accelerating micro- and nano-electromechanical systems applications Herein, using first-principles calculations we demonstrate cobalt mono-telluride (CoTe) monolayer as an outstanding candidate for achieving large piezoelectric, flexoelectric and flexomagnetic response down to monolayer limit. CoTe monolayer is found to be a semiconductor with a sizable bandgap of 0.48 eV, which is shown tunable by in-plane uniaxial or biaxial strains. This is because that the puckered structure and intrinsic charge distribution asymmetry along the perpendicular direction, enables the structure and properties heavily relied on external strain. In addition, such CoTe monolayer exhibits an out-of-plane polarization up to ~21 pC/m with a flexoelectric coefficient of ~0.08 nC/m and a flexomagnetic coefficient of 89.59 μBÅ, to our knowledge, surpassing most of other 2D binary systems. These findings not only clarify the fundamental structure and properties of CoTe monolayer, but also solidify the feasibility and designability of constructing piezo/flexoelectric and flexomagnetic devices on CoTe basis.