Antiferromagnet topological insulators with ${\mathit{AB}}_{2}C$ Heusler structure

The band structures, partial density of states, and electronic configuration of several ${\mathit{AB}}_{2}C$ full-Heusler compounds have been simulated using local-density approximation (LDA)$+$$U$. Results show that full-Heusler compounds with half-filled $d$ orbitals and $d^5$$d^5$$s^2$$p^6$ electronic structures can also form topological insulators, which will double the range of topological insulator candidates. The band structures of full-Heusler compounds are affected by the covalent bondings of $A$-$B$ and $B$-$C$ jointly. The spin-up electrons and spin-down electrons influence the orbitals respectively, which leads to the magnetism of the materials, and all full-Heusler compounds with the magnetic moments ∼9${\mu }_{\mathrm{B}}$ are antiferromagnets, which may provide a new design of a tunable optical modulator.

Figure 1

Band structures of GdPtBi (1a) and YV${}_2$Bi (1b), where the dotted line marks the bands with Γ${}_6$ symmetry and the dash-dotted line is that of Γ${}_8$ symmetry. The heavy line marks spin up and thin line is spin down.

Figure 2

The PDOS of YV${}_2$Bi, where positive values on the $y$ axis denote spin up and negative ones denote spin down.

Figure 3

The energy difference between Γ${}_6$ and Γ${}_8$ bands ($E_{\mathrm{\Gamma }6}$-$E_{\mathrm{\Gamma }8}$) of YV${}_2$Bi as a function of different $U$ values of Y and V atoms.

Figure 4

The spin-up orbital of electronic configuration of YV${}_2$Bi at different energy levels.

Figure 5

The energy difference between Γ${}_6$ and Γ${}_8$ bands ($E_{\mathrm{\Gamma }6}$-$E_{\mathrm{\Gamma }8}$) as a function of the lattice constant.