Multiple Dirac cones and Lifshitz transition in a two-dimensional Cairo lattice as a Hawking evaporation analogue

The linear energy–momentum dispersion of Dirac cones offers a unique platform for mimicking the fantastical phenomena in high energy physics, such as Dirac fermions and black hole (BH) horizons. Three types of Dirac cones (I, III, and II) with different tilts have been proposed individually in specific materials but lack of integral lattice model. Here, we demonstrated the three types of Dirac cones inherited in a π-conjugated Cairo lattice of double-degenerate d _π and p _z orbitals by means of tight-binding (TB) approach, which paves a way for the design of two-dimensional (2D) Dirac materials. From first-principles calculations, we predicted a candidate material, penta-NiSb₂ monolayer, to achieve these multiple Dirac cones and the Lifshitz transition between different Dirac cones driven by external biaxial strain. The coexistence of the three types of Dirac cones renders penta-NiSb₂ monolayer a promising 2D fermionic analogue to simulate the event-horizon evaporation with a high Hawking temperature. (paper)