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.