Optical circular dichroism in an antiperovskite Dirac semimetal

We theoretically study selective circular dichroism in an antiperovskite type Dirac semimetal, which hosts Dirac fermions with high total angular momentum J. We find that unconventional circular dichroism depends on J : In J =1/2 Dirac fermion, nonzero circular dichroism is generated in J_z - J'_z = ±1, where J_z and J'_z are the z-component of J of the conduction band minimum and the valance band maximum around Dirac points, respectively. It is noted that this ±1 reflects on the spin angular momentum of the polarization of the applied light. On the other hand, in J =3/2 Dirac fermion, the nonzero circular dichroism is triggered in J_z - J'_z = ±3. Its origin is shown in this presentation.