Valley-polarized Quantum Anomalous Hall and Topological Metal Phase in Rashba induced pseudospin-1 lattice

Abstract: We study the topological properties of Rashba spin-orbit coupling and exchange coupling induced pseudospin-$1$ system Dice lattice under the influence of a staggered electric potential and magnetization. The band structure and topological phases of the system are investigated and compared with pseudospin-$\frac{1}{2}$ system honeycomb lattice. Under individual influence of the staggered electric field and magnetization, the system undergoes a distinct phase transition: (i) a staggered electric potential drives the system from a quantum anomalous Hall $(C_n = 2)$ to a valley polarized quantum anomalous Hall phase $(C_n = -1)$ associated with edge modes with a flip in the chirality; while (ii) a staggered magnetization changes the system to a topological metal associated with unconventional antichiral edge bands, from a topological insulator. These results are further supported by calculations of the Chern numbers, Hall conductance, zigzag, and armchair edge states. Our findings enhance the understanding of new topological phases in the 2D pseudospin-1 system and open up a new platform to explore the anti-chiral edge states.