Hydrostatic strain-induced topological phase of KNa₂Sb

Topological insulators are novel state of quantum matter that have a bulk band gap like an ordinary insulator, but have protected conducting states by time reversal symmetry on their edge or surface. The spin-orbit coupling can play an important role in these materials, resulting in a band inversion at time reversal invariant momenta (TRIM) points. The topological phase and the effect of the hydrostatic pressure on the electronic structure and topological phase of the KNa₂Sb compound are investigated by using both first-principles calculations and ab-initio based tight-binding computations. Under hydrostatic lattice strain until 5.6%, the KNa₂Sb compound is semimetal with zero energy band gap and has an inverted band order. In this pressure, the Z₂ invariants of this compound are calculated using the parity analysis at TRIM points and evolution of wannier charge centers at the six TRIM plane. The calculated surface states at (0 0 1) surface show a single Dirac cone exists on the XGW line at the surface Brillouin zone. To investigate the stability of KNa₂Sb compound the phonon dispersions and elastic tensors of this compound in the cubic structure are calculated.

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Recommended citation: Shahram Yalameha, Zahra Nourbakhsh, Aminollah Vaez, Journal of Magnetism and Magnetic Materials 468, 279-286.