The TiNI monolayer: a two-dimensional system with promising ferroelastic, topological, and thermoelectric properties

We demonstrate using first-principles calculations that the TiNI monolayer simultaneously exhibits favorable ferroelastic, topological, and thermoelectric properties. Specifically, we discover a 90° lattice rotation with a moderate switching barrier of 56 meV per atom when a uniaxial tensile strain is applied to the system. Besides, the monolayer is found to be an intrinsic topological insulator with an inverted band structure, as characterized by the Z2 invariant of 1 and the presence of Dirac-like edge states at a critical width of 5.6 nm. Moreover, the thermoelectric ZT value of the system can reach as high as 1.4 at 600 K by fine tuning the carrier concentration. Collectively, these findings make the TiNI monolayer a promising multifunctional material to meet the various application requirements of nanoelectronic devices.