Tunable circular dichroism and valley polarization in the modified Haldane model

Abstract

We study the polarization dependence of optical absorption for a modified Haldane model, which exhibits antichiral edge modes in the presence of sample boundaries and has been argued to be realizable in transition metal dichalcogenides or Weyl semimetals. A rich optical phase diagram is unveiled, in which the correlations between perfect circular dichroism, pseudospin andvalley polarization can be tuned independently upon varying the Fermi energy. In particular, perfect circular dichroism and valley polarization are achieved simultaneously. This combination of optical properties suggests some interesting photonic device functionality (e.g., light polarizer) which could be combined with valleytronics applications (e.g., generation of valley currents). ; M.V. acknowledges the Graphene Flagship grant and the Department of Physics of Tohoku University for its hospitality. The research leading to these results has received funding from "La Caixa" Foundation by supporting M.V. S.R. was supported by the European Union Horizon 2020 research and innovation programme under Grant Agreement No. 696656 (Graphene Flagship). ICN2 is funded by the CERCA Programme/Generalitat de Catalunya, and is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706). R.S. acknowledges JSPS Kakenhi (Grant No. JP18H01810). N.T.H. acknowledges JSPS Kakenhi (Grant No. JP18J10151). ; Peer reviewed